This document summarizes the background, study design, purpose, findings, and key messages emerging from the formative research conducted for ENRICH in Shinyanga and Singida regions, Tanzania. Formative research conducted between December 2017 and January 2018 was designed to better understand the current maternal, infant, and young child nutrition practices from multiple perspectives. The research also included household trials (trials of improved practices or TIPs) for pregnant women and young children. The formative research aimed to identify priority behaviours and key messages aligned with improving consumption of nutritious foods and micronutrient supplements by pregnant women and young children, as well as to identify opportunities within the local context to promote these behaviours. These results have informed the development of a behaviour change intervention (BCI) strategy for ENRICH.