Background: Positive behaviour support emphasises the impact of contextual variables to enhance participation, choice, and quality of life. This study evaluates a sequence for implementing changes to key contextual variables for 4 individuals. Interventions were maintained and data collection continued over a 3-year period. Method: Functional assessments were conducted with 4 individuals with exceptionally severe challenging behaviours. Interventions were based on the multi-element model of behavioural support (LaVigna & Willis, 2005a). Dependent variables were behavioural ratings of (1) frequency, (2) episodic severity, (3) episodic management difficulty, and measures of (4) mental health status, and (5) quality of life. The intervention sequence was low arousal environment, rapport building, predictability, functionally equivalent skills teaching, and differential reinforcement strategies. Results: Substantial reductions in target behaviours were observed, along with incremental improvement in mental health scores and quality-of-life scores. Conclusion: The study demonstrates the efficacy of positive behaviour support for people with exceptionally severe behaviour in individually designed services. (Contains 3 figures and 5 tables.)