There is sufficient evidence that psychosocial stimulation (PS) benefits children's neurocognitive behavior, however, there is no information on how it works when delivered through an Unconditional Cash Transfer (UCT) platform for poor rural population in developing countries. The objective of this study is to measure effects of adding PS for children of lactating mothers enrolled to receive UCT with health education (HE) on neurocognitive behavior of children in rural Bangladesh.The study will be conducted at 11 unions of Ullapara sub-district in Bangladesh. The study is a cluster randomized controlled trial with three-arms; (i) PS and UCT with HE (ii) UCT with HE and iii) Comparison arm. The cluster will be considered as an old Ward of a Union, the lowest tier of local government system in rural Bangladesh. There are three old Wards in a union. These three clusters will be randomized to one of the three arms. Similarly, randomization will be done for each 11 Unions and then 11 clusters will be assigned to an arm. Eighteen participants will be recruited from each cluster randomly (n = 196 in each arm). The intervention designed for one year includes UCT with HE for the poor as a safety net program in rural Bangladesh with or without PS. An age-based curriculum of PS is already available for Bangladeshi children and this will be administered by trained local women; play leaders (PL) in intervention clusters. The government of Bangladesh is providing UCT of taka 500 ($6.25) as maternity allowance per month with HE. The primary outcomes will be cognitive, motor and language composite scores measured by Bayley-III and behavior using Wolke's behavior rating scale. The secondary outcomes will be children and mothers' growth, family food security status, health seeking behavior, mothers' depressive symptoms and self-esteem and violence against mothers.The study will provide a unique opportunity to assess an integrated early childhood development intervention using UCT platform to mitigate developmental delays in poor vulnerable children of rural Bangladesh.ClinicalTrials.gov NCT03281980, registered on September 13, 2017.