Past studies have investigated relationships between peer acceptance and peer-rated social behaviors. However, relatively little is known about the manner in which indices of well-being such as optimism and positive affect may predict peer acceptance above and beyond peer ratings of antisocial and prosocial behaviors. Early adolescence—roughly between the ages of 9 and 14—is a time in the life span in which individuals undergo a myriad of changes at many different levels, such as changes due to cognitive development, pubertal development, and social role redefinitions. The present study investigated the relationship of self-reported affective empathy, optimism, anxiety (trait measures), and positive affect (state measure) to peer-reported peer acceptance in 99 (43% girls) 4th and 5th grade early adolescents. Because our preliminary analyses revealed gender-specific patterns, hierarchical regression analyses were conducted to investigate the predictors of peer acceptance separately for boys and for girls. Girls’ acceptance of peers was significantly predicted by higher levels of empathy and optimism, and lower positive affect. For boys, higher positive affect, lower empathy, and lower anxiety significantly predicted peer acceptance. The results emphasize the importance of including indices of social and emotional well-being in addition to peer-ratings in understanding peer acceptance in early adolescence, and urge for more research on gender-specific peer acceptance.