This systematic review evaluates the strength of the evidence that community health workers' (CHW) provision of family planning (FP) services in low- and middle-income countries is effective. In a search of eight databases, articles were screened by study design and outcome measure and ranked by strength of evidence. Only randomized trials, longitudinal studies with a comparison group, and pre-test/post-test studies met inclusion criteria. A total of 56 studies were included. Of those studies with relevant data, approximately 93 percent indicated that CHW FP programs effectively increased the use of modern contraception, while 83 percent reported an improvement in knowledge and attitudes concerning contraceptives. Based on these findings, strong evidence exists for promoting CHW programs to improve access to FP services. We recommend a set of best practice guidelines that researchers and program managers can use to report on CHW FP programs to facilitate the translation of research to practice across a wide range of settings.