diff --git a/CHANGELOG.md b/CHANGELOG.md
index e4fdf500c9a..367b8396af2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,6 +31,9 @@ Updates:
   ([#1269](https://github.com/open-telemetry/opentelemetry-specification/pull/1269))
 - Add requirement that the SDK allow custom generation of Trace IDs and Span IDs
   ([#1006](https://github.com/open-telemetry/opentelemetry-specification/pull/1006))
+- Add default ratio when TraceIdRatioSampler is specified by environment variable but
+  no ratio is.
+  ([#1322](https://github.com/open-telemetry/opentelemetry-specification/pull/1322))
 
 ## v0.7.0 (11-18-2020)
 
diff --git a/specification/sdk-environment-variables.md b/specification/sdk-environment-variables.md
index e4b7b9b4aae..cce243028aa 100644
--- a/specification/sdk-environment-variables.md
+++ b/specification/sdk-environment-variables.md
@@ -27,7 +27,7 @@ Known values for `OTEL_TRACE_SAMPLER` are:
 
 Depending on the value of `OTEL_TRACE_SAMPLER`, `OTEL_TRACE_SAMPLER_ARG` may be set as follows:
 
-- For `traceidratio` and `parentbased_traceidratio` samplers: Sampling probability, a number in the [0..1] range, e.g. "0.25".
+- For `traceidratio` and `parentbased_traceidratio` samplers: Sampling probability, a number in the [0..1] range, e.g. "0.25". Default is 1.0 if unset.
 
 ## Batch Span Processor