This memo describes the dynamic allocation of shared IPv4 addresses to clients using DHCPv4. Address sharing allows a single IPv4 address to be allocated to multiple active clients simultaneously@ with each client being differentiated by a unique set of transportlayer source port numbers. The necessary changes to existing DHCPv4 client and server behavior are described@ and a new DHCPv4 option for provisioning clients with shared IPv4 addresses is included. Due to the nature of IP address sharing@ some limitations to its applicability are necessary. This memo describes these limitations and recommends suitable architectures and technologies where address sharing may be utilized.