• Summary: Two groups of social workers (n = 19, n = 13) carried out two different forms of assessment session, one involving an ASI (Addiction Severity Index) interview (n = 40) and one without (n = 43). After the sessions the social workers were requested to assess both the clients' experience and their own experience of the session. The clients also reported their own experience of the sessions.

• Findings: The results show that the social workers' assessment of the clients' experience differs from the clients' own assessments regarding the sub-scales of alliance and the clients' sense of own competence. However, no difference was observed between the social workers' assessment and the clients' negative experiences of the sessions. The results show the importance of asking the clients for their views when testing new ways of working. This will provide a more balanced picture as social workers are inclined to perceive the negative aspects and misjudge other experiences. The two different forms of session, with or without the ASI, did not affect the social workers' assessment of the clients' experience of the sessions.

• Applications : Testing of new methods of working in social work.