diff --git a/compiler/noirc_frontend/src/elaborator/mod.rs b/compiler/noirc_frontend/src/elaborator/mod.rs
index 0f9d22ca9b5..50b39757fda 100644
--- a/compiler/noirc_frontend/src/elaborator/mod.rs
+++ b/compiler/noirc_frontend/src/elaborator/mod.rs
@@ -10,7 +10,10 @@ use crate::{
         UnresolvedTraitConstraint, UnresolvedTypeExpression,
     },
     hir::{
-        def_collector::{dc_crate::CompilationError, errors::DuplicateType},
+        def_collector::{
+            dc_crate::{CompilationError, UnresolvedStruct, UnresolvedTrait, UnresolvedTypeAlias},
+            errors::DuplicateType,
+        },
         resolution::{errors::ResolverError, path_resolver::PathResolver, resolver::LambdaContext},
         scope::ScopeForest as GenericScopeForest,
         type_check::TypeCheckError,
@@ -27,10 +30,10 @@ use crate::{
     macros_api::{
         BlockExpression, CallExpression, CastExpression, Expression, ExpressionKind, HirExpression,
         HirLiteral, HirStatement, Ident, IndexExpression, Literal, MemberAccessExpression,
-        MethodCallExpression, NodeInterner, NoirFunction, PrefixExpression, Statement,
+        MethodCallExpression, NodeInterner, NoirFunction, NoirStruct, PrefixExpression, Statement,
         StatementKind, StructId,
     },
-    node_interner::{DefinitionKind, DependencyId, ExprId, FuncId, StmtId, TraitId},
+    node_interner::{DefinitionKind, DependencyId, ExprId, FuncId, StmtId, TraitId, TypeAliasId},
     Shared, StructType, Type, TypeVariable,
 };
 use crate::{
@@ -68,6 +71,7 @@ mod expressions;
 mod patterns;
 mod scope;
 mod statements;
+mod traits;
 mod types;
 
 use fm::FileId;
@@ -206,11 +210,12 @@ impl<'context> Elaborator<'context> {
         // the resolver filters literal globals first
         for global in items.globals {}
 
-        for alias in items.type_aliases {}
-
-        for trait_ in items.traits {}
+        for (alias_id, alias) in items.type_aliases {
+            this.define_type_alias(alias_id, alias);
+        }
 
-        for struct_ in items.types {}
+        this.collect_traits(items.traits);
+        this.collect_struct_definitions(items.types);
 
         for trait_impl in &mut items.trait_impls {
             this.collect_trait_impl(trait_impl);
@@ -1100,4 +1105,72 @@ impl<'context> Elaborator<'context> {
             });
         }
     }
+
+    fn define_type_alias(&mut self, alias_id: TypeAliasId, alias: UnresolvedTypeAlias) {
+        self.file = alias.file_id;
+        self.local_module = alias.module_id;
+
+        let generics = self.add_generics(&alias.type_alias_def.generics);
+        self.resolve_local_globals();
+        self.current_item = Some(DependencyId::Alias(alias_id));
+        let typ = self.resolve_type(alias.type_alias_def.typ);
+        self.interner.set_type_alias(alias_id, typ, generics);
+    }
+
+    fn collect_struct_definitions(&mut self, structs: BTreeMap<StructId, UnresolvedStruct>) {
+        // This is necessary to avoid cloning the entire struct map
+        // when adding checks after each struct field is resolved.
+        let struct_ids = structs.keys().copied().collect::<Vec<_>>();
+
+        // Resolve each field in each struct.
+        // Each struct should already be present in the NodeInterner after def collection.
+        for (type_id, typ) in structs {
+            self.file = typ.file_id;
+            self.local_module = typ.module_id;
+            let (generics, fields) = self.resolve_struct_fields(typ.struct_def, type_id);
+
+            self.interner.update_struct(type_id, |struct_def| {
+                struct_def.set_fields(fields);
+                struct_def.generics = generics;
+            });
+        }
+
+        // Check whether the struct fields have nested slices
+        // We need to check after all structs are resolved to
+        // make sure every struct's fields is accurately set.
+        for id in struct_ids {
+            let struct_type = self.interner.get_struct(id);
+            // Only handle structs without generics as any generics args will be checked
+            // after monomorphization when performing SSA codegen
+            if struct_type.borrow().generics.is_empty() {
+                let fields = struct_type.borrow().get_fields(&[]);
+                for (_, field_type) in fields.iter() {
+                    if field_type.is_nested_slice() {
+                        let location = struct_type.borrow().location;
+                        self.file = location.file;
+                        self.push_err(ResolverError::NestedSlices { span: location.span });
+                    }
+                }
+            }
+        }
+    }
+
+    pub fn resolve_struct_fields(
+        &mut self,
+        unresolved: NoirStruct,
+        struct_id: StructId,
+    ) -> (Generics, Vec<(Ident, Type)>) {
+        let generics = self.add_generics(&unresolved.generics);
+
+        // Check whether the struct definition has globals in the local module and add them to the scope
+        self.resolve_local_globals();
+
+        self.current_item = Some(DependencyId::Struct(struct_id));
+
+        self.resolving_ids.insert(struct_id);
+        let fields = vecmap(unresolved.fields, |(ident, typ)| (ident, self.resolve_type(typ)));
+        self.resolving_ids.remove(&struct_id);
+
+        (generics, fields)
+    }
 }
diff --git a/compiler/noirc_frontend/src/elaborator/traits.rs b/compiler/noirc_frontend/src/elaborator/traits.rs
new file mode 100644
index 00000000000..e7018d900d8
--- /dev/null
+++ b/compiler/noirc_frontend/src/elaborator/traits.rs
@@ -0,0 +1,196 @@
+use std::collections::BTreeMap;
+
+use iter_extended::vecmap;
+use noirc_errors::Location;
+
+use crate::{
+    ast::{FunctionKind, TraitItem, UnresolvedGenerics, UnresolvedTraitConstraint},
+    hir::{
+        def_collector::dc_crate::UnresolvedTrait, def_map::ModuleId,
+        resolution::path_resolver::StandardPathResolver,
+    },
+    hir_def::{
+        function::{FuncMeta, HirFunction},
+        traits::{TraitConstant, TraitFunction, TraitType},
+    },
+    macros_api::{
+        BlockExpression, FunctionDefinition, FunctionReturnType, Ident, ItemVisibility,
+        NoirFunction, Param, Pattern, UnresolvedType, Visibility,
+    },
+    node_interner::{FuncId, TraitId},
+    token::Attributes,
+    Generics, Type, TypeVariable, TypeVariableKind,
+};
+
+use super::Elaborator;
+
+impl<'context> Elaborator<'context> {
+    pub fn collect_traits(&mut self, traits: BTreeMap<TraitId, UnresolvedTrait>) {
+        for (trait_id, unresolved_trait) in &traits {
+            self.interner.push_empty_trait(*trait_id, unresolved_trait);
+        }
+
+        for (trait_id, unresolved_trait) in traits {
+            let generics = vecmap(&unresolved_trait.trait_def.generics, |_| {
+                TypeVariable::unbound(self.interner.next_type_variable_id())
+            });
+
+            // Resolve order
+            // 1. Trait Types ( Trait constants can have a trait type, therefore types before constants)
+            let _ = self.resolve_trait_types(&unresolved_trait);
+            // 2. Trait Constants ( Trait's methods can use trait types & constants, therefore they should be after)
+            let _ = self.resolve_trait_constants(&unresolved_trait);
+            // 3. Trait Methods
+            let methods = self.resolve_trait_methods(trait_id, &unresolved_trait, &generics);
+
+            self.interner.update_trait(trait_id, |trait_def| {
+                trait_def.set_methods(methods);
+                trait_def.generics = generics;
+            });
+
+            // This check needs to be after the trait's methods are set since
+            // the interner may set `interner.ordering_type` based on the result type
+            // of the Cmp trait, if this is it.
+            if self.crate_id.is_stdlib() {
+                self.interner.try_add_operator_trait(trait_id);
+            }
+        }
+    }
+
+    fn resolve_trait_types(&mut self, _unresolved_trait: &UnresolvedTrait) -> Vec<TraitType> {
+        // TODO
+        vec![]
+    }
+
+    fn resolve_trait_constants(
+        &mut self,
+        _unresolved_trait: &UnresolvedTrait,
+    ) -> Vec<TraitConstant> {
+        // TODO
+        vec![]
+    }
+
+    fn resolve_trait_methods(
+        &mut self,
+        trait_id: TraitId,
+        unresolved_trait: &UnresolvedTrait,
+        trait_generics: &Generics,
+    ) -> Vec<TraitFunction> {
+        self.local_module = unresolved_trait.module_id;
+        self.file = self.def_maps[&self.crate_id].file_id(unresolved_trait.module_id);
+
+        let mut functions = vec![];
+
+        for item in &unresolved_trait.trait_def.items {
+            if let TraitItem::Function {
+                name,
+                generics,
+                parameters,
+                return_type,
+                where_clause,
+                body: _,
+            } = item
+            {
+                let old_generic_count = self.generics.len();
+
+                let the_trait = self.interner.get_trait(trait_id);
+                let self_typevar = the_trait.self_type_typevar.clone();
+                let self_type = Type::TypeVariable(self_typevar.clone(), TypeVariableKind::Normal);
+                let name_span = the_trait.name.span();
+
+                self.add_generics(generics);
+                self.add_existing_generics(&unresolved_trait.trait_def.generics, trait_generics);
+                self.add_existing_generic("Self", name_span, self_typevar);
+                self.self_type = Some(self_type.clone());
+
+                let func_id = unresolved_trait.method_ids[&name.0.contents];
+                self.resolve_trait_function(
+                    name,
+                    generics,
+                    parameters,
+                    return_type,
+                    where_clause,
+                    func_id,
+                );
+
+                let arguments = vecmap(parameters, |param| self.resolve_type(param.1.clone()));
+                let return_type = self.resolve_type(return_type.get_type().into_owned());
+
+                let generics = vecmap(&self.generics, |(_, type_var, _)| type_var.clone());
+
+                let default_impl_list: Vec<_> = unresolved_trait
+                    .fns_with_default_impl
+                    .functions
+                    .iter()
+                    .filter(|(_, _, q)| q.name() == name.0.contents)
+                    .collect();
+
+                let default_impl = if default_impl_list.len() == 1 {
+                    Some(Box::new(default_impl_list[0].2.clone()))
+                } else {
+                    None
+                };
+
+                let no_environment = Box::new(Type::Unit);
+                let function_type =
+                    Type::Function(arguments, Box::new(return_type), no_environment);
+
+                functions.push(TraitFunction {
+                    name: name.clone(),
+                    typ: Type::Forall(generics, Box::new(function_type)),
+                    location: Location::new(name.span(), unresolved_trait.file_id),
+                    default_impl,
+                    default_impl_module_id: unresolved_trait.module_id,
+                });
+
+                self.generics.truncate(old_generic_count);
+            }
+        }
+        functions
+    }
+
+    pub fn resolve_trait_function(
+        &mut self,
+        name: &Ident,
+        generics: &UnresolvedGenerics,
+        parameters: &[(Ident, UnresolvedType)],
+        return_type: &FunctionReturnType,
+        where_clause: &[UnresolvedTraitConstraint],
+        func_id: FuncId,
+    ) {
+        let old_generic_count = self.generics.len();
+        self.scopes.start_function();
+
+        // Check whether the function has globals in the local module and add them to the scope
+        self.resolve_local_globals();
+
+        self.trait_bounds = where_clause.to_vec();
+
+        let kind = FunctionKind::Normal;
+        let def = FunctionDefinition {
+            name: name.clone(),
+            attributes: Attributes::empty(),
+            is_unconstrained: false,
+            is_comptime: false,
+            visibility: ItemVisibility::Public, // Trait functions are always public
+            generics: generics.clone(),
+            parameters: vecmap(parameters, |(name, typ)| Param {
+                visibility: Visibility::Private,
+                pattern: Pattern::Identifier(name.clone()),
+                typ: typ.clone(),
+                span: name.span(),
+            }),
+            body: BlockExpression { statements: Vec::new() },
+            span: name.span(),
+            where_clause: where_clause.to_vec(),
+            return_type: return_type.clone(),
+            return_visibility: Visibility::Private,
+        };
+
+        self.elaborate_function(NoirFunction { kind, def }, func_id);
+        let _ = self.scopes.end_function();
+        // Don't check the scope tree for unused variables, they can't be used in a declaration anyway.
+        self.trait_bounds.clear();
+        self.generics.truncate(old_generic_count);
+    }
+}
diff --git a/compiler/noirc_frontend/src/elaborator/types.rs b/compiler/noirc_frontend/src/elaborator/types.rs
index 4c8364b6dda..b0d29cffde7 100644
--- a/compiler/noirc_frontend/src/elaborator/types.rs
+++ b/compiler/noirc_frontend/src/elaborator/types.rs
@@ -4,7 +4,10 @@ use iter_extended::vecmap;
 use noirc_errors::{Location, Span};
 
 use crate::{
-    ast::{BinaryOpKind, IntegerBitSize, UnresolvedTraitConstraint, UnresolvedTypeExpression},
+    ast::{
+        BinaryOpKind, IntegerBitSize, NoirTypeAlias, UnresolvedGenerics, UnresolvedTraitConstraint,
+        UnresolvedTypeExpression,
+    },
     hir::{
         def_map::ModuleDefId,
         resolution::{
@@ -26,7 +29,10 @@ use crate::{
         HirExpression, HirLiteral, HirStatement, Path, PathKind, SecondaryAttribute, Signedness,
         UnaryOp, UnresolvedType, UnresolvedTypeData,
     },
-    node_interner::{DefinitionKind, ExprId, GlobalId, TraitId, TraitImplKind, TraitMethodId},
+    node_interner::{
+        DefinitionKind, DependencyId, ExprId, GlobalId, TraitId, TraitImplKind, TraitMethodId,
+        TypeAliasId,
+    },
     Generics, Shared, StructType, Type, TypeAlias, TypeBinding, TypeVariable, TypeVariableKind,
 };
 
@@ -1435,4 +1441,27 @@ impl<'context> Elaborator<'context> {
             }
         }
     }
+
+    pub fn add_existing_generics(&mut self, names: &UnresolvedGenerics, generics: &Generics) {
+        assert_eq!(names.len(), generics.len());
+
+        for (name, typevar) in names.iter().zip(generics) {
+            self.add_existing_generic(&name.0.contents, name.0.span(), typevar.clone());
+        }
+    }
+
+    pub fn add_existing_generic(&mut self, name: &str, span: Span, typevar: TypeVariable) {
+        // Check for name collisions of this generic
+        let rc_name = Rc::new(name.to_owned());
+
+        if let Some((_, _, first_span)) = self.find_generic(&rc_name) {
+            self.push_err(ResolverError::DuplicateDefinition {
+                name: name.to_owned(),
+                first_span: *first_span,
+                second_span: span,
+            });
+        } else {
+            self.generics.push((rc_name, typevar, span));
+        }
+    }
 }