[Excerpt] The COMET (Construction Organizing Membership Education Training) is an educational program utilized by building trades unions to generate rank and file support for organizing new members. Since 1996, the Building and Construction Trades Department of the AFL-CIO has been sponsoring COMET training in multi-trade settings for its fifteen affiliates. Between 1997 and 1998, the Department undertook a systematic evaluation of its multi-trade COMET programs to determine their impact on attitudes toward organizing as well as on the nature and extent of organizing activities. This article summarizes the lessons the Department learned. Among other conclusions, the evaluation reaffirmed that COMET training is an effective way to build internal support for external organizing and that local unions using the COMET appear to be more deeply engaged in organizing than those not using this innovative labor education program.