The easy and cost effective interworking of Distributed Queue Dual Bus (DQDB) and Asynchronous Transfer Mode (ATM) protocols is of prime importance for the evolution of the broadband integrated services digital network (B-ISDN) and the long-term success of MANs as tributary networks. In this paper, we study several practically useful scenarios for the interworking of ATM Customer Premises Networks (CPN) through a transit DQDB network. Suitable Interworking Unit (IWU) protocols are presented and compared. It is shown that the most advantageous solution in terms of service quality and IWU simplicity and robustness is the use of a Connection Oriented (CO) DQDB service exploiting the Queued-Arbitrated mode of access. Also, the provisions required in the definition of a CO DQDB service are pointed out. Finally, the implementation of an IWU applying the ideas presented is outlined.