Reported in this paper are preliminary results from a study designed to examine the development of self-esteem and mastery of mothers with infants of very low birth weight (VLBW). (The term "self-esteem" is defined as the degree of positive or negative self-regard reported by an individual, and "mastery" is defined as the extent to which an individual believes he or she has a causal role in determining the outcome of events importantly affecting his or her life.) A total of 20 low-income Mexican-American mothers who gave birth to VLBW infants (1,250 grams or less) participated in the study along with 20 socioeconomically matched mothers having infants of normal birthweight. Self-esteem was assessed on the Rosenberg Self-Esteem Scale, and mastery was assessed on the Pearlin Mastery Scale. Results suggested that mothers in both groups possessed normally high levels of self-esteem, regardless of their infants' birthweights, and that mastery in mothers of VLBW infants was associated with self-esteem (that is, the higher the mother's self-esteem, the higher her mastery, and vice versa). (MP)