diff --git a/core/api/src/main/java/org/onosproject/net/pi/runtime/PiActionGroup.java b/core/api/src/main/java/org/onosproject/net/pi/runtime/PiActionGroup.java
new file mode 100644
index 0000000..57fab9d
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/pi/runtime/PiActionGroup.java
@@ -0,0 +1,190 @@
+/*
+ * Copyright 2017-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.net.pi.runtime;
+
+import com.google.common.annotations.Beta;
+import com.google.common.base.MoreObjects;
+import com.google.common.base.Objects;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Maps;
+
+import java.util.Collection;
+import java.util.Map;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Action group of a protocol-independent pipeline.
+ */
+@Beta
+public final class PiActionGroup {
+
+    /**
+     * Type of action group.
+     */
+    public enum Type {
+        /**
+         * Load-balancing among different members in a group.
+         */
+        SELECT
+    }
+
+    private final PiActionGroupId id;
+    private final Type type;
+    private final ImmutableSet<PiActionGroupMember> members;
+
+    private PiActionGroup(PiActionGroupId id, Type type, ImmutableSet<PiActionGroupMember> members) {
+        this.id = id;
+        this.type = type;
+        this.members = members;
+    }
+
+    /**
+     * Returns the identifier of this action group.
+     *
+     * @return action group identifier
+     */
+    public PiActionGroupId id() {
+        return id;
+    }
+
+    /**
+     * Returns the type of this action group.
+     *
+     * @return action group type
+     */
+    public Type type() {
+        return type;
+    }
+
+    /**
+     * Returns the members of this action group.
+     *
+     * @return collection of action members.
+     */
+    public Collection<PiActionGroupMember> members() {
+        return members;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        PiActionGroup that = (PiActionGroup) o;
+        return id == that.id &&
+                Objects.equal(type, that.type) &&
+                Objects.equal(members, that.members);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(id, type, members);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this)
+                .add("groupId", id)
+                .add("type", type)
+                .add("members", members)
+                .toString();
+    }
+
+    /**
+     * Returns a new builder of action groups.
+     *
+     * @return action group builder
+     */
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    /**
+     * Builder of action groups.
+     */
+    public static final class Builder {
+
+        private PiActionGroupId id;
+        private Type type;
+        private Map<PiActionGroupMemberId, PiActionGroupMember> members = Maps.newHashMap();
+
+        private Builder() {
+            // hides constructor.
+        }
+
+        /**
+         * Sets the identifier of this action group.
+         *
+         * @param id action group identifier
+         * @return this
+         */
+        public Builder withId(PiActionGroupId id) {
+            this.id = id;
+            return this;
+        }
+
+        /**
+         * Sets the type of this action group.
+         *
+         * @param type action group type
+         * @return this
+         */
+        public Builder withType(Type type) {
+            this.type = type;
+            return this;
+        }
+
+        /**
+         * Adds one member to this action group.
+         *
+         * @param member action group member
+         * @return this
+         */
+        public Builder addMember(PiActionGroupMember member) {
+            members.put(member.id(), member);
+            return this;
+        }
+
+        /**
+         * Adds many members to this action group.
+         *
+         * @param members action group members
+         * @return this
+         */
+        public Builder addMembers(Collection<PiActionGroupMember> members) {
+            members.forEach(this::addMember);
+            return this;
+        }
+
+        /**
+         * Creates a new action group.
+         *
+         * @return action group
+         */
+        public PiActionGroup build() {
+            checkNotNull(id);
+            checkNotNull(type);
+            checkArgument(members.size() > 0, "Members cannot be empty");
+            return new PiActionGroup(id, type, ImmutableSet.copyOf(members.values()));
+        }
+    }
+}