Traditional African vegetables have recently received considerable attention for their contribution to food and nutrition security and opportunities for enhancing smallholder livelihoods. Promoting the production and consumption of traditional vegetables is expected to enhance household nutrition among urban and rural households. The Good Seed Initiative (GSI) program promoted production and consumption of nutrient-dense traditional African vegetables in Arusha region in Tanzania to reduce malnutrition through diet diversification. We estimated the impact of promotion activities on households, women, and children's dietary diversity. The study used cross-sectional data from 258 and 242 households in intervention and control regions, respectively, and applied matching techniques and inverse probability weighting to control for unobserved heterogeneity and selection bias, which could otherwise bias the outcome estimates. We found that households benefiting from traditional vegetable promotion and demand creation activities had significantly higher dietary diversity of children under 5 yr and women in reproductive age. We found no significant impact of promotion activities on households’ dietary diversity. The policy implication is that scaling up promotional and demand creation activities to encourage consumers to grow and eat traditional African vegetables would be an important element in initiatives to increase dietary diversity, particularly for children under 5 and women in Tanzania.