diff --git a/CHANGELOG.md b/CHANGELOG.md
index 144d10bf371..d8b1bd014f3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,9 @@ release.
 
 ### OpenTelemetry Protocol
 
+- Adding requirement to implement at least one of two transports: `grpc` or `http/protobuf`.
+  ([#1790](https://github.com/open-telemetry/opentelemetry-specification/pull/1790/files))
+
 ### SDK Configuration
 
 ## v1.5.0 (2021-07-08)
diff --git a/spec-compliance-matrix.md b/spec-compliance-matrix.md
index 878dc5e6393..1f9d617c8cd 100644
--- a/spec-compliance-matrix.md
+++ b/spec-compliance-matrix.md
@@ -159,7 +159,7 @@ Note: Support for environment variables is optional.
 | [OTLP](specification/protocol/otlp.md)                                         |          |    |   |    |             |      |        |     |      |     |      |       |
 | OTLP/gRPC Exporter                                                             | *        | +  | + | +  | +           |      | +      |     | +    | +   | +    | +     |
 | OTLP/HTTP binary Protobuf Exporter                                             | *        | +  | - | +  | [-][py1106] | +    | +      |     |      | -   | -    | -     |
-| OTLP/HTTP JSON Protobuf Exporter                                               | *        | +  | - | +  | [-][py1003] |      | -      |     |      | -   | -    | -     |
+| OTLP/HTTP JSON Protobuf Exporter                                               |          | +  | - | +  | [-][py1003] |      | -      |     |      | -   | -    | -     |
 | OTLP/HTTP gzip Content-Encoding support                                        | X        | +  | - | +  | +           | +    | -      |     |      | -   | -    | -     |
 | Concurrent sending                                                             |          | -  | + | +  | [-][py1108] |      | -      |     | +    | -   | -    | -     |
 | Honors retryable responses with backoff                                        | X        | +  |   | +  | +           | +    | -      |     |      | -   | -    | -     |
diff --git a/specification/protocol/exporter.md b/specification/protocol/exporter.md
index 19cefd80b72..c62111c9935 100644
--- a/specification/protocol/exporter.md
+++ b/specification/protocol/exporter.md
@@ -41,9 +41,15 @@ export OTEL_EXPORTER_OTLP_METRICS_ENDPOINT=https://collector.example.com/v1/metr
 
 ### Specify Protocol
 
-Currently, OTLP has more than one transport protocol it can support, e.g.
-`grpc`,  `http/json`, `http/protobuf`.   As of 1.0 of the specification, there
-*is no specified default, or configuration via environment variables*.  We
+Currently, OTLP supports the following transport protocols:
+
+- `grpc` for protobuf-encoded data using gRPC wire format over HTTP/2 connection
+- `http/protobuf` for protobuf-encoded data over HTTP connection
+- `http/json` for JSON-encoded data over HTTP connection
+
+SDKs MUST support either `grpc` or `http/protobuf` and SHOULD support both. They also MAY support `http/json`.
+
+As of 1.0 of the specification, there *is no specified default, or configuration via environment variables*.  We
 reserve the following environment variables for configuration of protocols in
 the future: