We highlight several critical challenges that must be addressed to accelerate the advancement of the science on recruitment and retention of ethnically diverse older adults into health research. These include the relative lack of attention by researchers to methodological issues related to recruitment and retention of ethnically diverse populations and the inadequacy of funding to advance systematically this field. We describe strategies used by the Resource Centers on Minority Aging Research and other National Institute of Aging-funded programs to advance the science of recruitment of ethnically diverse older adults. Finally, we propose a set of broad recommendations designed to generate a body of evidence on successful methods of recruitment and retention of ethnically diverse populations in health research. To eliminate health disparities and better understand aging processes in ethnically diverse populations, much more research is needed on effective strategies for increasing minority enrollment in health research. Comparative effectiveness research on more intensive recruitment and retention methods, which are often needed for including diverse populations, will require dedicated funding and concerted efforts by investigators.