Cotherapy in a training relationship with a senior therapist~supervisor and a trainee~junior leader is presented. A structured training year with planned sessions for the junior leader to lead the group alone, as well as intensive supervision, is described. The training relationship is seen as evolving into an egalitarian, collegial working relationship. An incidental benefit of this cotherapy approach is that additional opportunities are provided for group members to work through attitudes, feelings, and behaviors associated with attachment, interpersonal relationship (autonomy and affiliation), separation, and loss. Potential drawbacks and applications are also noted.Cotherapy has evolved during the ascendance of group therapy as an acceptable mode of psychological intervention. This paper focuses on one particular approach to cotherapy, in which one senior therapist functions as the supervisor of the cotherapist. In this approach, the cotherapist is acknowledged explicity to be a trainee, although one training goal is for the cotherapy relationship to evolve into an egalitarian, collegial collaboration.