Inadequate care during early childhood can lead to long-term deficits in skill development. Parenting programs are promising tools for improving parenting practices and opportunities for healthy development. We implemented a non-masked cluster-randomized controlled trial in rural China in order to assess the effectiveness of an integrated home-visitation program that includes both psychosocial stimulation and health promotion at fostering development and health outcomes of infants and toddlers in rural China. All 6-18 month-old children of two rural townships and their main caregiver were enrolled. Villages were stratified by township and randomly assigned to intervention or control. Specifically, in September 2015 we assigned 43 clusters to treatment (21 villages, 222 caregiver-child dyads) or control (22 villages, 227 caregiver-child dyads). In the intervention group, community health workers delivered education and training on how to provide young children with psychosocial stimulation and health care (henceforth psychosocial stimulation and health promotion) during bi-weekly home visits over the period of one year. The control group received no home visits. Primary outcomes include measures of child development (i.e. the Bayley Scales of Infant and Toddler Development, third edition— or Bayley-III) and health (i.e. measures of morbidity, nutrition, and growth). Secondary outcomes are measures of parenting practices. Intention-to-treat (ITT) effects show that the intervention led to an improvement of 0$·$24 standard deviations (SD) [95% CI 0$·$04 SD-0$·$44 SD] in cognitive development and to a reduction of 8$·$1 [95% CI 3$·$8– 12$·$4] percentage points in the risk of diarrheal illness. In addition, we find positive effects on parenting practices mirroring these results. We conclude that an integrated psychosocial stimulation and health promotion program improves development and health outcomes of infants and toddlers (6– 30 month-old children) in rural China. Because of low incremental costs of adding program components (that is, adding health promotion to psychosocial stimulation programs), integrated programs may be cost-effective.