Prior research has determined that low-income students lose more ground over the summer than their higher-income peers. Prior research has also shown that some summer learning programs can stem this loss, but we do not know whether large, district-run, voluntary programs can improve students' outcomes. To fill this gap, The Wallace Foundation launched the National Summer Learning Study in 2011. The five-year study offers the first-ever assessment of the effectiveness of large-scale, voluntary, district-run, summer learning programs serving low-income elementary students. This resource contains the following technical appendixes that accompany the report: (1) Randomization Design and Implementation; (2) Statistical Analysis; (3) Data Collection; (4) Hypothesized Mediators and Moderators of Summer Program Effects; and (5) Results from Regression Models with Covariates. [For the full report, see ED561140; for the brief, see ED561107.]