Prior research on cause‐related marketing (CM) shows that congruencies between for‐profit and nonprofit organizational missions and target markets affect consumers' perceptions of the partnership fit, and their subsequent response to CM promotions. The current work explores how congruencies between for‐profit and nonprofit sizes influence consumers' perceptions of the partnership fit, and subsequently, their attitudes toward CM efforts. Study 1 shows that consumers perceive a low degree of organizational partnership fit between a small for‐profit and large nonprofit (relative to other partnership configurations). Study 2 shows the nature of donated resources can affect organizational partnership fit perceptions, such that donations of needed goods (vs. money) can improve consumers' perceptions of partnership fit between a small for‐profit and large nonprofit. Study 3 shows that organizational cause congruency and organizational size both independently contribute to perceptions of organizational partnership fit.