Two objectives drive most research: detecting variation and identifying factors that account for it. Mental health services researchers do not have to look far to find differences. Rates of illness prevalence and treatment receipt vary, sometimes sharply. This month’s lead article reports a 14-fold difference between states in the rate of stimulant treatment of children—.4% of children in Alaska and 5.1% in Delaware. Douglas C. McDonald, Ph.D., and Sarah Kuck Jalbert, M.A., M.S., also found a sixfold difference in the rate for adults (page 1079). Amanda Toler Woodward, Ph.D., analyzed data from three U.S. population surveys and found that people seeking behavioral health treatment fell into five different classes based on choice of nine provider types. Patients born before 1946 favored family physicians, although these providers also played a substantial role in treating younger Americans (page 1087). Asian Americans and Pacific Islanders (AA/PI) are a rapidly increasing U.S. population group. Little is known about their service use—a knowledge gap that is widened by researchers’ tendency to combine heterogeneous subgroups into the AA/PI category. In examining four years of discharge data for psychiatric hospitalizations in Hawaii, Tentine Sentell, Ph.D., and colleagues found differences not only between AA/PI patients and white patients but also between AA/PI subgroups (page 1095). Finally, when Carl I. Cohen, M.D., and Leslie Marino, M.D., M.P.H., took a closer look at racial-ethnic differences in reported rates of psychotic symptoms, they found a shared factor—distress—that accounted for the variation (page 1103).