To analyze the disorders of their patients, psychotherapists often have to get insight in adaptive dynamical systems. Analysis of dynamical systems usually is performed using mathematical techniques. Such an analysis is not precisely the type of reasoning performed in psychotherapy practice. In this article, it is shown how practical reasoning about dynamic properties of adaptive dynamical systems within psychotherapy can be described using a high-level logical language to describe dynamics. Using this language, an executable model has been developed of the dynamics of eating regulation disorders. Based on this model, a number of simulation traces have been generated, both for well-functioning situations and for different types of malfunctioning situations that correspond to the first phase of well-known disorders such as anorexia (nervosa), obesitas, and bulimia. Next, it is shown how such traces can be automatically analyzed against a number of dynamic properties. © 2006, Sage Publications. All rights reserved.