  We present initial results from a long-baseline radial velocity survey for
massive binaries in the cluster Westerlund 1. Four systems are examined: the
dust-producing WC binary W239, the double-lined eclipsing binary W13, and the
single-lined B0 supergiants W43a and W3003. Finally, the evolutionary
implications for the population of massive stars in Westerlund 1 are discussed.
