Low participation in nutrition supplementation can cause the true effects of the supplements to be underestimated. Participation behaviors and their associations with personal and socio-cultural characteristics were examined qualitatively and quantitatively when food and micronutrient supplements were provided jointly to pregnant women in rural Bangladesh to find ways to improve effectiveness of nutrition supplementation by enhancing participation. In-depth interviews (IDI) were conducted with 24 multiparous women in Matlab, Bangladesh to elicit information on pregnancy-related cultural issues and their experiences with supplement use. Quantitative analysis was conducted by using data from Maternal and Infant Nutrition Interventions at Matlab (MINIMat), a randomized controlled trial (factorial design of 2 food and 3 micronutrient groups) that collected extensive information on participants’ (n=4,436 pregnant women) characteristics and program features. Supplement consumption was monitored monthly. Levels of participation were examined in terms of initiation and utilization of food, micronutrient, or combined supplements. Relationships between participation behaviors and potential factors were examined through multiple regressions. Text analysis of the IDI revealed that culture-specific beliefs, attitudes, perceptions, and practices set boundaries to pregnant women’s behaviors, including supplement consumption. Based on these results, a psychosocial model was developed to guide the quantitative analysis. Results from the quantitative analysis corroborated the findings from the qualitative analysis. Support from husbands or mothers-in-law, advice from program providers, positive attitudes toward supplementation, and participants’ autonomy were positively associated with supplement consumption, while cultural obligations, a possible cesarean delivery caused by a large-sized baby, poor appetite, and no perceived benefits were negatively associated with the consumption. Generally, participants consumed micronutrient more than food supplementation. Women who started to consume food before micronutrient supplements showed better participation than women with the reverse sequence. Sharing of food packages with others and replacing home meals with the supplements were prevalent. Only 10 % of participants consumed both types of nutrition supplements persistently. These results show that food supplementation needs more attention for persistent participation when provided with micronutrient supplementation. To enhance pregnant women’s participation, it is essential to understand socio-cultural environments of participants along with their perspectives about supplementation and design a program that addresses these issues.