The thesis consists of three chapters focusing on social class, social class is an identity by which societies organise themselves hierarchically and can shape a person’s life opportunities and experiences. Chapter one is a systematic review of UK studies researching if and how being working-class impacts engaging with psychological therapy for mental health difficulties. It found that being working-class was associated with difficulties engaging in psychological therapy for mental health difficulties. A possible reason was finding therapy unhelpful or aversive and one of the suggested changes to aid engagement was having a therapist with a similar social class status. However, there remains a significant gap in the literature regarding the underlying mechanisms resulting in engagement difficulties and evidence-base methods to address these. Chapter two is an exploration into the experiences of working-class trainee clinical psychologists and how they acculturated to UK Doctorate in Clinical Psychology (DClinPsy) training. Thematic analysis was used on semi-structured interviews and found a common trajectory of acculturation that was impacted by whether class was an invisible or visible social identity. Chapter three discusses pertinent topics of clinical and theoretic implications present in the systematic review and empirical research study. These topics consist of social identity being multifaceted and intersecting, with social class just one aspect of this. Also, exploring how social class is not currently a protected characteristic despite inequalities and discrimination, neither is there a consensus on how to conceptualise or measure it.