This article presents the first analysis of the impact of mandated minimum-staffing ratios on nursing hours of care and skill mix in adult medical and surgical and definitive-observation units in a convenience sample of 68 acute hospitals participating in the California Nursing Outcomes Coalition project. Findings, stratified by unit type and hospital size, reveal expected changes as hospitals made observable efforts toward regulatory compliance. These data cannot affirm compliance with ratios per shift, per unit, at all times; however, they give evidence of overall compliance. Assessment of the impacts of the mandated ratios on two common indicators of patient care quality, the incidence of patient falls and the prevalence of pressure ulcers, did not reveal significant changes despite research linking nurse staffing with these measures. These findings contribute to understanding unit level impacts of regulatory staffing mandates and the preliminary effect of this legislation on core quality of care indicators.