In the current climate of theoretical change, psychoanalysis is seeking a theory of interaction. The authors propose that principles of interactive organization documented in infant research have analogues in adult treatment. A systems model of the integration of self- and mutual regulation is used to draw analogies, but not one-to-one correspondences, between infant research and adult psychoanalysis. The authors specifically address how self- and mutual regulation impact on each other, arguing that internal and relational processes are simultaneously organized, in relation to each other, at all developmental levels.