Decades of research conducted using field experiments and quasi-experiments have enabled us to accumulate causal evidence on the effectiveness of onboarding and socialization programs (SPs) across various contexts including employment, higher education, and military services. However, the literature is devoid of an integrated conceptual framework and a quantitative review evaluating the effect of such SPs on reducing newcomer turnover and its boundary conditions. In this study, we draw from a configurational approach to categorize strategic components of SPs, propose bundles of these components based on extant theories in the socialization literature, and examine the moderating effects of these bundles on the retention benefits of SPs. Combining 168 effect sizes from 83 field experiments, our meta-analysis reveals a significant overall effect size of OR = 1.46, suggesting that, on average, the odds of retention are 1.46 times higher for newcomers participating in a SP compared to newcomers in the control group. Our results also indicate that SPs' beneficial effects on newcomer retention are greater when they include the components of identifying effective task behaviors, encouraging proactivity, and facilitating social integration, a bundle aimed at satisfying key psychological needs identified by self-determination theory. We further demonstrate that the retention benefits associated with SP participation increase when the SPs are delivered in-person and of our studies were not preregistered.Songqi Liu played a lead role in conceptualization, data curation, formal analysis, investigation, methodology, project administration, writing-original draft, and writing-review and editing. Daniel Watts played a supporting role in conceptualization, data curation, formal analysis, investigation, methodology, writing-original draft, and writing-review and editing. Jie Feng played a supporting role in conceptualization, investigation, methodology, writingoriginal draft, and writing-review and editing. Ying Wu played a supporting role in conceptualization, data curation, formal analysis, investigation, methodology, and project administration. Jingfeng Yin played a supporting role in conceptualization, data curation, formal analysis, investigation, and methodology.