The review found that it was possible to calculate a common measure of effect size (the standardized mean difference) in 35 studies, with 21 of the studies focusing on cognitive empathy and 14 on affective empathy. Although there are many definitions of empathy, one current and inclusive definition is provided by Cohen and Strayer (1996). They view empathy as "the ability to understand and share in another's emotional state or context." This definition acknowledges that empathy is both a cognitive process (the ability to understand another's emotional state) and an affective capacity (the sharing of the emotional state of another). Criminologists have postulated that those who offend and those who act antisocially have less empathy than those who do not offend. This is because individuals who share and/or comprehend another's negative emotional reaction, which occurs as a result of their own antisocial or aggressive behavior, may be inhibited and less inclined to continue with this behavior or act in an antisocial or aggressive manner in the future. The results of this meta-analysis confirm this hypothesis, as the studies reviewed suggest that empathy and offending are negatively related; however, the strength of this relationship is apparently influenced by a number of factors. Cognitive empathy has been found to have a stronger negative relationship with offending than affective empathy. This may be due to the scale used to measure cognitive empathy. The most important finding of the meta-analysis is that the empathy differences between offenders and nonoffenders disappeared when controlling for socioeconomic status in the nonoffending and offending populations. Similarly, when intelligence was controlled, the difference between offenders and nonoffenders disappeared in studies of sex offenders, and it was reduced in mixed offender studies. Possible explanations for these findings are discussed. In order to assess whether empathy has an influence on offending behavior independently of other factors, variables with a known association with offending behavior must be controlled. Offender and control groups should be matched as closely as possible on individual variables such as impulsivity and intelligence. Further, controlling for family and demographic variables could provide insight into the mechanism whereby empathy might influence behavior. 5 tables and 99 references