This study was conducted to investigate the factors that affect the duration of breastfeeding in low and middle income women, and to determine if low income women have a greater incidence of decreased duration of breastfeeding. Specifically, the effects of early introduction of formula and solid food and mother’s perceived inadequate milk supply, on the duration of breastfeeding, was researched. A questionnaire was developed and one on one interviews conducted on 147 women who breastfed a baby within the past five years. Data analysis included crosstabulation of selected variables, descriptive analyses, and chi square analyses. Results indicated that the majority of the women surveyed introduced formula early, were long term breastfeeders, between the ages of 30-39, and college graduates. There was no difference in duration of breastfeeding between women of low and middle incomes, however, women of middle income terminated breastfeeding early to return to work or school and tended to introduce formula earlier than low income women. Furthermore, mothers who introduced formula or solid foods early, were generally short term breastfeeders. Mothers who introduced formula and solid foods early cited insufficient milk supply as their main reason for terminating breastfeeding. Therefore, mothers perceived to have an insufficient milk supply, tend to introduce formula and solid foods early, thus, contributing to a possible decrease in duration of breastfeeding. / Master of Science