Background Despite its importance within behavioural intervention, it remains unclear how best to achieve high procedural fidelity. This paper reviewed studies on improving procedural fidelity of behavioural interventions for individuals with intellectual and developmental disabilities (IDD). Method A systematic literature search was conducted, which identified 20 studies meeting inclusion criteria. Data were extracted on study design, participant characteristics, intervention, target behaviours, effect sizes, maintenance, generalization and social validity. A quality rating was also applied. Results A total of 100 participants took part in the included studies. Most participants were teachers working with children in school settings. There was a significant positive correlation between level of procedural fidelity and client outcomes. Feedback was the most commonly employed intervention to improve procedural fidelity. Conclusions More research should be conducted in environments with high levels of variability such as community homes to determine how to reach and maintain high levels of procedural fidelity.