Pasteurized donor human milk provides a safe and desirable alternative when a parent's own milk is insufficient or unavailable. Currently, the demand for donor human milk exceeds the available supply. Little is known about the beliefs breastfeeding individuals have about milk bank donation. The aims of this exploratory study were to (a) provide a preliminary estimate of how well intention can be predicted, and to suggest which of the global constructs of the Reasoned Action Approach has the most influence on intention; and (b) identify the salient, top-of-the-mind beliefs underlying the intention to donate some of the milk an individual is currently producing to a milk bank. An exploratory, cross-sectional study design, based on the Reasoned Action Approach, was used to measure the theory's global constructs and elicit beliefs underlying the intention to donate milk of lactating individuals (N = 118) living in Indiana, Illinois, Missouri, and Kentucky. Thematic and frequency analyses and multiple regression were performed. Quantitative analyses found that injunctive norm and the autonomy component of perceived behavioral control were independently associated with intention. Qualitative analyses identified the advantages (e.g., help and save babies, won't waste milk), referents who support (e.g., husband, family), and facilitators (e.g., having a convenient, close location, having more knowledge and information) of donating milk. This research provides insight into how milk banks might recruit and retain donors. Additional quantitative research with a larger sample is necessary to confirm the preliminary findings of this study.