Frontline staff are a valuable asset within an intellectual and developmental disability service. Their work dictates the overall standard of care delivered by the organization. However, there is evidence that the research relating to effective practice is having little impact on the competencies displayed by staff in the real-world setting. Therefore, a scoping review of published literature was conducted to investigate potential explanations for the inadequate dissemination of evidence-based practice in this sector. Systematic searches of relevant databases identified 156 papers for inclusion in the review. Practices in which staff were trained were categorized as either behavioral interventions or “other” interventions. The behavioral category was sub-divided into: a) assessment; b) antecedent; c) consequence and, d) “mixed” practices. Although the studies reviewed provided staff training across a range of practices, many empirically supported interventions were not utilized. Despite rigorous scientific support for strategies such as functional communication training and noncontingent reinforcement, the literature did not robustly evaluate effective protocols to disseminate these practices to frontline staff. The review also highlighted a continued reliance on individualized training packages, rather than the implementation of empirically supported training models. Finally, results showed that a relatively small number of included studies examined the impact of staff training on service user outcomes and adult service users were underrepresented across all intervention categories. Findings provide a potential explanation for the apparent disconnect between theoretical advancements and practice in the applied setting and are discussed in relation to approaches to staff training.