Background. Long-term care settings have frequently been targeted as environments prone to deficiencies in quality and resultant negative effects on resident safety. The use of minimum nurse staffing ratios has been proposed as a way to improve the quality of care for long-term care residents. However, the American Nursing Association has criticized the appropriateness of ratios for the determination of staffing needs. A more appropriate staffing methodology is one that is based on a measure of intensity that takes into consideration the aggregate population of patients and the associated roles and responsibilities of the nursing staff. The purpose of this study is threefold: (1) to determine the difference between the hours of care required by residents and reported staffing, (2) to examine whether differences can be explained by organizational characteristics, and (3) to determine if differences influence the quality of resident care. Methods. A descriptive/correlational analysis was performed using a cross-section of the administrative data contributed by Ohio nursing homes to both CMS's Online Survey and Reporting Systems (OSCAR) and the Minimum Data Set version 2.0 (MDS 2.0) in 2000. The resulting sample was 690 facilities. Acuity-based staffing was calculated using the RUG-III groupings and standardized times obtained from the Center for Medicaid and Medicare Services (CMS). Quality measures were aggregated to the nursing home level using indicators derived from the CMS Minimum Data Set and deficiencies reported in OSCAR. Findings. Acuity-based Total Nurse staffing was found to be significantly higher (4.07 hours per patient day) than reported Total Nurse staffing (3.46 hours per resident day). More than 70% of the Ohio nursing homes have lower staffing than that required based on acuity. Non-profit ownership status was reflective of higher amount of staffing in all categories (RN, LPN, NA, total). The difference between reported staffing and calculated staffing had a significant influence on the prevalence of no range of motion (ROM), the use of antipsychotics, and pressure ulcers. Similarly, the staffing difference influenced the variation in the number of cited deficiencies and the number of substandard quality of care deficiencies. Conclusions. Acuity-based staffing approaches would likely increase the demand for nursing staff in nursing homes where shortages are already common. Only 30% of Ohio nursing homes would be considered to have enough nursing staff if staffing standards were based on RUG-III acuity and time estimates. As negative differences between reported and acuity-based staffing increased, several quality outcomes were found to be negatively influenced, even controlling for organizational characteristics such as profit, size, location, and percent Medicaid.