This study uses national survey data to examine why charter school teachers are more likely to turnover than their traditional public school counterparts. We test whether the turnover gap is explained by different distributions of factors that are empirically and theoretically linked to turnover risk. We find that the turnover rate of charter school teachers was twice as high as traditional public school teachers in 2003-04. Differences in the distributions of our explanatory variables explained 61.0% of the total turnover gap. The higher proportions of uncertified and inexperienced teachers in the charter sector, along with the lower rate of union membership, were the strongest contributors to the turnover gap. Charter school teachers were more likely to self-report that working conditions motivated their decisions to leave the profession or move schools, although we found no measurable evidence that the actual working conditions of charter and traditional public schools were different. (Contains 5 tables.)