Authors included in this issue of the Journal of Clinical Psychology: In-Session come from diverse theoretical orientations but discuss methods of case conceptualization that share these assumptions: (1) that interpersonal patterns are salient to a good understanding of patient personality and problems and (2) that an individual formulation is helpful in responsively tailoring in-session processes to meet therapeutic goals. We believe these assumptions resonate with many practitioners working across settings, levels of severity, and theoretical orientations. Each author offers an overview of theory as well as a detailed case description that emphasizes the implications of each formulation for the subsequent process of therapy. A final paper provides commentary across the source papers. The issue is thus evocative not only about clinical practice issues but also of underlying theory. It speaks to the challenges and possibilities of transtheoretical integrated practice and research within our focal domain of common interest, interpersonal relationships.