The authors present a new transcript-based method for the assessment of therapeutic alliance ruptures and resolutions in psychotherapy-the Collaborative Interaction Scale (CIS)-and discuss the structure and theoretical background of the scale and the rating procedure. To assess interrater reliability, three raters independently evaluated 32 psychotherapy sessions (2,984 patient utterances and 2,984 therapist utterances) using the CIS, which demonstrated good interrater reliability (average kappa=.66-.81). In evaluating the relationship between therapist interventions and patient alliance rupture and collaborative processes, the authors found significant correlations between therapist negative interventions and patient alliance ruptures and among therapist positive interventions, patient collaborative processes, and indirect rupture markers. Results indicate that the CIS is a reliable rating system, useful in both empirical research and clinical assessments.