diff --git a/test.go b/test.go
index b1fc665..58cfbde 100644
--- a/test.go
+++ b/test.go
@@ -6,10 +6,17 @@ import (
 	"testing"
 )
 
+// Test is a test value: a value that, given an instance of a testing.T, can be
+// used to execute a single test.
 type Test interface {
 	Run(*testing.T)
 }
 
+// After defines the interface used for performing test cleanup. If a Test
+// value also implements After, that test's After method will be called after
+// all tests are run. Tests in a sequence will have their After methods called
+// in the reverse order of their Run methods; a test always runs its After
+// method after all of its children have completed their own After methods.
 type After interface {
 	After(*testing.T)
 }
diff --git a/tree.go b/tree.go
index 82e8b5b..222aa6d 100644
--- a/tree.go
+++ b/tree.go
@@ -75,7 +75,10 @@ func New(test Test) *Tree {
 	}
 }
 
-// Tree represents a node in a Tree of tests
+// Tree represents a node in a Tree of tests. Callers create Tree elements in
+// one of two ways: by calling New to create a new Tree with the provided test
+// as its root, or by calling the Child method on an existing Tree to add a
+// child node to the tree.
 type Tree struct {
 	test     Test
 	name     string