This study of mother-adult daughter communication uses qualitative methods to explore the appropriateness of including adult daughters as referents in the measurement of subjective norms (a behavioral theory construct) related to the use of mammography and other health-related tests and services. The methods were chosen to approximate as closely as possible the mother-adult daughter relationship in the context of daily life. This inductive approach contrasts with the deductive origins of the construct. A sample of nine Mexican and Filipina immigrant and U.S.-born mothers and their adult daughters was recruited. Data were collected in two phases: (a) videotaped observations of mother-daughter dyads discussing health-related topics and (b) follow-up interviews designed to obtain an emic (insider) perspective of the videotaped interaction. Results show that adult daughters influence their mothers' ability to navigate the health care system and contribute to health-related decision making and behavior, suggesting that it may be appropriate to include adult daughters in the assessment of subjective norms. (Contains 1 figure.)