The literature on critical thinking (CT) in counselling and therapy generally posits higher quality outcomes when CT is applied in therapeutic treatment. We critically examine support for the claim that CT improves clinical outcomes. The purported effects of CT are first identified by arguments in favour of using CT in therapeutic treatment, both in terms of its general efficacy and with regard to its applicability in professional counselling. We then underscore limitations in the current literature, highlighting mainly a gap between theory and practice. Overall, our results suggest that available evidence provides primarily inferential, rather than direct, support for the claim that CT positively influences therapy outcomes. We close the paper by proposing research questions to guide further empirical investigation.