Section I: Foundations of psychotherapy research:The Prehistory of Psychotherapy and Its Implications for Psychotherapy Science: Shamanism, Folk Medicine, Philosophy, and Religion -- Historical paths in psychotherapy Research.-The philosophy of psychotherapy science: Mainstream and alternative views -- Psychotherapia Academica Universitatis: A Philosophical Argument for the Academic Discipline of Psychotherapy -- Interpretation as a Cognitive Instrument. Psychotherapy Science as an Attempt to Pool Paradigm-based Systems of Interpretation -- Institutional parameters of psychotherapy education as a prerequisite for systematic psychotherapy research -- Theory-Building, Enriching, and Fact-Gathering: Alternative Purposes of Psychotherapy Research -- Section II. Psychotherapy process research: Introduction to psychotherapy process research -- Outlines of a general theory of the psychotherapy process. The clinical exchange as communicational field: Implications for theory and methodology.- The Relationship: How it Works.- Data analysis in psychotherapy research -- Quantitative approaches to treatment process, change process, and process-outcome research -- Current issues on group psychotherapy research: An overview.- The Process of Change in Psychotherapy: Common and Unique Factors -- Therapeutic alliance and alliance ruptures and resolutions: Theoretical definitions, assessment issues and research findings.- Positive emotions in psychotherapy: Conceptual propositions and research challenges -- Psychotherapeutic Process from the Psychotherapist's Perspective.- From a psychoanalytic narrative case study to quantitative single case research.- Qualitative methods in psychotherapy process research -- Applications of Qualitative and Mixed-Methods Counseling and Psychotherapy Research.- Interpretation-Driven Guidelines for Designing and Evaluating Grounded Theory Research: A Constructivist-Social Justice Approach.- Consensual QualitativeResearch (CQR) Methods for Conducting Psychotherapy Process Research.- Conversation analysis and psychotherapy process research.- A pragmatic approach to the study of therapeutic interaction: Towards an observational science of psychotherapy process. Section III. Psychotherapy outcome research: Quantitative psychotherapy outcome research: Methodological issues -- Qualitative methods in psychotherapy outcome research -- Outcome Research on Disorder-Specific Treatments: The Case of Grief Therapy -- Outcome research: Methods for Improving Outcome in Routine Care.- Psychotherapy outcome research and neuroimaging.