This study explored therapist characteristics associated with the development of working alliance in long-term therapies, up to 120 sessions. The quality of working alliance was rated by both patients (n = 201) and therapists (n = 61) at sessions 3, 12, 20 and every 20th successive session. Therapists' self-reported scores on the 'cold/detached' dimension of Inventory of Interpersonal Problems-64 tapping therapists' interpersonal style, such as being distanced, disconnected or indifferent, had a negative impact on the working alliance as rated both by patients and therapists. More professional training was associated with poorer quality of working alliance, as rated by patients. A trend indicated that more experienced therapists rated the alliance lower at all sessions. Therapists' report of better maternal care up to their adolescence had a positive impact on patients' rating of alliance. Clinical implications are discussed.