Objective: To explore the impact social class biases may have on the treatment of clients by psychological and psychotherapeutic professionals in Britain. Design: A cross-sectional on-line study among 156 psychological and psychotherapeutic professionals working in the NHS incorporating a comparison between two groups - video vignettes representing ‘lower’ and ‘upper’ class clients. Methods: The video vignette depicted a psychological assessment session of a client who had been referred by his general practitioner after incidences involving deliberate self-harm. The accent and dress of the client were varied. Study participants completed measures of clinical reasoning relating to diagnosis, risk and treatment, measures of their awareness of the influence of social class on their work and a social class brief implicit association test. Results: Within the context of this study participants tended not to discriminate against clients in relation to their class. However, they believed that a ‘lower-class’ client was more likely to receive an ‘alcohol or substance misuse’ diagnosis (p= .002; d=0.40). They also scored the ‘lower-class’ client as more motivated to make changes (p=.032; d=.29). Seeing a ‘lower-class’ client resulted in significantly higher scores indicating participants reflection on personal conflicts relating to their own social class and the impact such biases may have on their work. Conclusions: There was no general pattern of discrimination against clients in relation to their social class. This may be due to client class cues priming the psychologist to reflect on their position. Practitioner Points: •Training and professional development for Psychological and Psychotherapeutic Professionals in ways to raise awareness of their personal beliefs about social class may help reduce class bias. •Working with clients such professionals perceive to be a ‘lower’ class allows them to reflect on these personal beliefs.