The impact of size of residence on residents' opportunities for choice was examined for Australian adults with mental retardation who lived in staff-supported community residences housing one to five residents. Significantly greater choice was exercised by individuals living in smaller settings, even when personal characteristics of individual residents were controlled statistically. Staff presence was confounded with living-unit size. Analyses including both staff presence and living-unit size revealed strong effects of staff presence, with more choice displayed in settings with longer periods when no staff members were present. Size effects were less evident once the variability associated with staff presence had been accounted for. Results suggest that both staff presence and living-unit size are important predictors of choice.