This study sought to provide a comprehensive picture of maternal conceptualization of Perceived Insufficient Milk (PIM) using qualitative methods (semistructured interviews, free lists, and rankings) in Mexico. Two hundred and seven first-time mothers of infants younger than 6 months and mothers-to-be who were (or intended to be) breastfeeding were interviewed in waiting areas at a hospital and a health clinic in Mexico City, Mexico, from September 2000 to January 2001. Pattern searching and triangulation of the 3 qualitative methods indicated that women viewed crying as the chief symptom of PIM. Maternal diet and liquid intake were cited as both the most salient causes and treatments for PIM. The main coping strategy in the event of PIM was formula feeding. These findings highlight the need for addressing maternal concerns in relation to PIM, especially regarding the role of crying as the initiator of the PIM cycle. J Hum Lact. 22(3):277–286.