I have written previously about the stages of change and the processes of change , two important components of James Prochaska's transtheoretical model (TTM). The original TTM also had a third concept, the levels of change, which captures another feature that differentiates between psychotherapy schools. In this case, Prochaska was getting at the idea of a "theory of problem causation" that seen as the focus for psychotherapeutic efforts. Prochaska differentiated these theories of why people have problems from separate "theories of change," which represent the ways in which problems can be fixed. The TTM's processes of change are theories of change, while the levels represent theories of problem causation. Compared to the other two components of the TTM, the levels of change have received minimal research and have not proven strongly predictive of treatment outcomes. Perhaps for that reason, this construct has not been widely used in the health care arena....