diff --git a/RELEASE.md b/RELEASE.md
new file mode 100644
index 0000000..4924614
--- /dev/null
+++ b/RELEASE.md
@@ -0,0 +1,3 @@
+RELEASE_TYPE: minor
+
+This release changes the default value of `fullmatch` in `fromRegex` from `false` to `true`.
diff --git a/src/main/java/dev/hegel/Generators.java b/src/main/java/dev/hegel/Generators.java
index d476cc6..e5d4c13 100644
--- a/src/main/java/dev/hegel/Generators.java
+++ b/src/main/java/dev/hegel/Generators.java
@@ -590,12 +590,14 @@ public static DurationGenerator durations() {
     }
 
     /**
-     * Generates strings matching a (Python-compatible) regular expression.
+     * Generates strings matching a (Python-compatible) regular expression. By default the entire
+     * string matches the pattern; use {@link RegexGenerator#fullmatch(boolean) fullmatch(false)}
+     * to generate strings that merely contain a match.
      *
      * @param pattern the regex pattern
      * @return a regex generator
      */
-    public static Generator<String> fromRegex(String pattern) {
-        return new RegexGenerator(pattern);
+    public static RegexGenerator fromRegex(String pattern) {
+        return new RegexGenerator(pattern, true);
     }
 }
diff --git a/src/main/java/dev/hegel/generators/RegexGenerator.java b/src/main/java/dev/hegel/generators/RegexGenerator.java
index f0c2aa3..21eb868 100644
--- a/src/main/java/dev/hegel/generators/RegexGenerator.java
+++ b/src/main/java/dev/hegel/generators/RegexGenerator.java
@@ -5,20 +5,33 @@
 import dev.hegel.Generator;
 
 /**
- * Generates strings matching a (Python-compatible) regular expression. Always basic (one engine
- * call).
+ * Generates strings matching a (Python-compatible) regular expression. By default the entire
+ * string matches the pattern; use {@link #fullmatch(boolean) fullmatch(false)} to generate strings
+ * that merely contain a match. Always basic (one engine call).
  */
 public final class RegexGenerator implements Generator<String> {
     private final String pattern;
+    private final boolean fullmatch;
 
-    public RegexGenerator(String pattern) {
+    public RegexGenerator(String pattern, boolean fullmatch) {
         this.pattern = pattern;
+        this.fullmatch = fullmatch;
+    }
+
+    /**
+     * @param fullmatch whether the entire string must match the pattern (the default), or merely
+     *     contain a match somewhere within it
+     * @return a copy with the fullmatch behaviour set
+     */
+    public RegexGenerator fullmatch(boolean fullmatch) {
+        return new RegexGenerator(pattern, fullmatch);
     }
 
     /** @hidden */
     @Override
     public BasicGenerator<String> asBasic() {
-        CBORObject schema = CBORObject.NewMap().Add("type", "regex").Add("pattern", pattern);
+        CBORObject schema =
+                CBORObject.NewMap().Add("type", "regex").Add("pattern", pattern).Add("fullmatch", fullmatch);
         return new BasicGenerator<>(schema, Cbor::asString);
     }
 }
diff --git a/src/test/java/dev/hegel/ConformanceTest.java b/src/test/java/dev/hegel/ConformanceTest.java
index 8289867..556e0f1 100644
--- a/src/test/java/dev/hegel/ConformanceTest.java
+++ b/src/test/java/dev/hegel/ConformanceTest.java
@@ -43,6 +43,7 @@
 import java.time.ZoneOffset;
 import java.util.List;
 import java.util.Objects;
+import java.util.regex.Pattern;
 import org.junit.jupiter.api.Test;
 
 /** Behaviour/conformance suite exercising every generator against the real engine. */
@@ -194,7 +195,18 @@ void formatGenerators() {
         assertAllExamples(ipAddresses().v6(), s -> s.contains(":"));
         assertAllExamples(ipAddresses(), s -> s.contains(".") || s.contains(":"));
         assertAllExamples(uuids(), Objects::nonNull);
-        assertAllExamples(fromRegex("[0-9]{3}"), s -> s.matches(".*[0-9]{3}.*"));
+    }
+
+    @Test
+    void regexDefaultsToFullmatch() {
+        // By default the entire string matches the pattern (String.matches is a full match).
+        assertAllExamples(fromRegex("[0-9]{3}"), s -> s.matches("[0-9]{3}"));
+        // fullmatch(false) relaxes to contains-a-match: every example contains a match...
+        assertAllExamples(
+                fromRegex("[0-9]{3}").fullmatch(false),
+                s -> Pattern.compile("[0-9]{3}").matcher(s).find());
+        // ...and surrounding characters genuinely occur (findAny throws if no such example exists).
+        findAny(fromRegex("[0-9]{3}").fullmatch(false), s -> !s.matches("[0-9]{3}"));
     }
 
     @Test