This study estimated the effects of the work environment on the quality of care in intensive care units (ICUs). Nurses in ICUs with good work environments or high nurse staffing were significantly less likely to report poor or fair quality of care (odds ratio [OR] = 0.37-0.47), rationing of nursing care (OR = 0.38-0.76), and health care-associated infections (OR = 0.28-0.68). Favorable ICU work environments and adequate nurse staffing can predict better quality of care.