It is well known that one of the critical sources of TCP poor performance in multihop ad hoc networks lies in the TCP window mechanism that controls the amount of traffic sent into the network. In this paper, we propose a novel cross layer solution called “TCP Contention Control” that dynamically adjusts the amount of outstanding data in the network based on the level of contention experienced by packets as well as the throughput achieved by connections. Our simulation results show TCP Contention Control can drastically improve TCP performance over 802.11 multihop ad hoc networks.