We examined the associations of cognitive skills, math-related emotions and beliefs, and gender with responses to an arithmetic fluency intervention. Elementary school children with dysfluent arithmetic skills (N=69) participated in an arithmetic fluency intervention (with and without self-efficacy support) implemented in small groups in schools for 12 weeks. Hierarchical regression models including cognitive skills or math-related emotions and beliefs predicted 21% to 50% of the variation in the intervention response, i.e., improvement in arithmetic fluency. Cognitive skills were associated with the response mainly among boys, whereas math-related emotions and beliefs explained more among girls. Thus, both cognitive and non-cognitive factors and their interaction with gender should be considered when identifying non-responders who may need more individually tailored support at school.