The current work proposes a Secure Group Membership Verification (SGMV) protocol for IP multicast. The aim of the SGMV protocol is to allow any valid members of a multicast group to verify the membership of the group without a (trusted) third party vouching for a complete membership list. SGMV allows a valid member of the multicast group to verify the membership of the group on its own and in real-time. This achieved by requiring other valid members to respond to a membership-query message issued by a querying member. Two underlying principles of the current SGMV approach are the independence of the SGMV protocol from the underlying multicast routing protocol and the independence from the group key management protocol(s) employed for the multicast group.