Gender differences in negotiation are typically explained by processes that concern women (e.g., women anticipate backlash for assertive behavior). Research has begun to suggest that processes that concern men (e.g., men want to be seen as real men) also help to explain gender differences. However, these 2 approaches typically remain disconnected. Thus, we examined both types of processes in 3 studies examining people's beliefs about the causes of gender differences in negotiation (total N = 931). Our studies showed that people endorsed to a similar, and sometimes even greater, extent processes that concern men as underlying gender differences in negotiation. Moreover, people's beliefs about the causes of gender differences in negotiation were related to perceptions of the effectiveness of different diversity initiatives (i.e., interventions to reduce inequities) and willingness to support them.