This evaluation study provides information about the implementation and outcomes of the 21st Century Community Learning Centers (21st CCLC) program in West Virginia, from September 2015 through May 2016, in which 12,388 students participated overall. The report draws on information from online surveys of directors of thirty six 21st CCLC programs…

Background: Cluster-randomized experiments that assign intact groups such as schools or school districts to treatment conditions are increasingly common in educational research. Such experiments are inherently multilevel designs whose sensitivity (statistical power and precision of estimates) depends on the variance decomposition across levels.…