The Housing & Children’s Healthy Development Study (HCHD) is a randomized controlled trial (RCT) using housing choice voucher (HCV) waitlists in two sites (Cleveland, OH and Dallas, TX) to investigate the impact of the HCV on child development. The sample includes 895 voucher families with 1,231 children, who were aged between 3 and 10 at the time of the baseline interviews (2017–2018). At baseline researchers collected biomarkers from children and their primary caregivers (mostly mothers), direct measures of children’s emotional and cognitive development, and measures that support analyzing hypothesized mechanisms by which the HCV program might affect children. Such mechanisms include housing affordability (which may free resources for children’s enrichment), housing and neighborhood conditions, and parental health and stress. The 3-Year Follow-Up Report presents impact estimates based on telephone follow-up surveys conducted in 2020–2021. Unfortunately, the Covid-19 pandemic prevented in-person follow-up interviews, which meant that the study team could not collect direct measures of child development. Results nevertheless provide strong evidence that HCV receipt is associated with improvements in housing affordability, housing size, neighborhood safety, and reduced hypertension and parental stress among primary caregivers.