Opponents of charter schools argue these schools "cream-skim" the best students from traditional public schools and push out hard-to-educate students. This paper reviews 22 studies of enrollment issues related to student achievement, special education status, English proficiency, and student discipline in US charter schools. Of the 22 studies, nine use student level data to rigorously test for evidence of strategic enrollment. While the charter sector as a whole tends to serve fewer special education students and English language learners, there is much within-sector variation. Over all, there is very little evidence of systematic "cream-skimming" or "push-out" in US charter schools.