Critical systems heuristics (CSH) has been influential in the development of critical systems thinking. However, it is a relatively underutilised method compared with soft systems approaches such as soft systems methodology (SSM) and cognitive mapping. This may be in part due to the complexity of ideas underpinning CSH. Core ideas with which users must feel confident include boundary critique, coercion, emancipation, and “is” vs “ought to be” framings. These ideas were the subject of the early discourse surrounding CSH, which considered the role of boundary critique in systems research, the extent to which CSH could meaningfully address coercion, and the claims of CSH as an emancipatory approach. The purpose of this review is to provide clarity on these key concepts by reflecting on how they have been addressed in the CSH literature to date. We find that CSH has been applied in a range of problem contexts and is most frequently applied to address coercion or power asymmetries. CSH research is frequently associated with advocacy for marginalised groups, and we believe this is a natural extension of the methodological emancipation to which CSH aspires. In providing an overview of the key ideas underpinning CSH, we hope to lower the barrier to application for systems researchers and practitioners.