This article presents a review of the literature on the use of Outcome Measures (OMs) in counselling and psychotherapy, done by the author as part of her research (to be reported later) into how transactional analysis practitioners use OMs in TA contracting, diagnosis and treatment planning. A wide range of non-TA literature is presented, various OMs are described, practitioners’ positive and negative perceptions of them are described as well what they tend to do instead of using OMs. It is reported how few counsellors and psychotherapists utilise OMs as part of their clinical practice. This article explores the issues and give more depth and detail into the ‘pros and cons’ of OM use within TA practice and is intended to initiate discussions of the topic alongside the research study.