Progressive counting (PC), a variant of the counting method, is a recently developed trauma resolution procedure that appears to be efficient and well tolerated. One hundred and nine mental health professionals who experienced a PC session rated their perception of the relative prevalence and importance of various possible mechanisms of effect. Multiple factors were endorsed as having contributed to treatment effect, including emotional processing, desensitization, various aspects of the procedure leading to a sense of mastery over the memory, integrating/making sense of what happened, dual focus/distraction/distancing, relaxation, and therapist presence/interactions. In the follow-up study, 26 mental health professionals undergoing a PC session wrote comments on their experience following each round of imaginal exposure. Informal analysis of these comments found a similar diversity of experiences and possible mechanisms of effect, and highlighted the importance of having the imaginal exposure’s ending representing as complete a resolution as possible. The findings support the possibility of multiple mechanisms contributing to PC’s effect.