The 3GPP network specification is currently undergoing major updates toward Beyond 3G. The evolved 3GPP Network will support interworking with multiple including non-3GPP radio access networks, and support mobility between them. It will furthermore support personal area networks and moving networks. Generally, 3GPP is moving in the direction of an all-IP network. This article gives an overview of current Beyond 3G trends in 3GPP, and particularly introduces a new 3GPP Study Item on Network Composition. The concept of Network Composition was developed by the EU project Ambient Networks. Whereas 3GPP until now assumes static networking relations, Network Composition addresses a dynamic, generic establishment of control-plane interworking between the heterogeneous network types of today, such as 3GPP core networks, non-3GPP operator networks,access networks, and Personal Area Networks.