Th ere are a number of theories that one might attempt to apply when working with transgender clients. Always, the bottom line should be the approach that is best indicated for the individual client, not the preferred approach of the therapist. When working with transgender clients who have no other mental health issues, choice of approach boils down to the question of causality and whether this lies in subtle social infl uences or is biologically based. Most current theorists hedge their bets by saying the cause may be a combination of both biological and psychosocial infl uences. Th e fact is that no one really knows beyond a doubt, so we can only use an educated guess and go forward within the edict of “Do no harm.”