> **††** <mark>All program recipients in a subset of 33 villages in 6 communes, including but not limited to those participants randomly sampled for the policy experiment, were included in the mechanism experiment sample. The mechanism experiment relied on household-level randomization.</mark>

<mark>Section 3 presents descriptive findings on the cultural and socioeconomic context as well as models of economic agency (Study 1). Some of these quantitative measures were developed based on formative qualitative research, including interviews and focus groups. Quantitative data on models of agency from the Niger sample are complemented with prediction data collected from an U.S.-based online convenience sample (N=302) and were g</mark> athered ex post <mark>through the</mark> CloudResearch <mark>platform.</mark> <mark>In Section 4, we explore psychosocial mechanisms of the highly effective multi-faceted interventions tested in Bossuroy et al. (2022) by conducting additional analyses of the baseline and follow-up surveys (Study 2). This four-arm policy experiment (N=4,712) included a control arm, which was a national safety net program that provided monthly cash transfers of US$38.95 (in 2016 PPP) to the lowest income households in rural villages in Niger. All three treatment arms included a core set of economic components similar to the broader literature on multifaceted interventions (Banerjee, Duflo, Goldberg, et al., 2015), including the monthly cash transfers plus savings group formation, micro-entrepreneurship training, group coaching and market access facilitation. To those components, the Psychosocial arm added two psychosocial interventions, a community sensitization and a 1-week life skills training (described in greater detail in Section 4). The Capital arm instead added a lump sum cash grant of US$311 (in 2016 PPP). The Full arm included all components.</mark> <mark>Here, we focus on the mechanisms that drove the impacts of the Psychosocial and Full arms (i.e., those that included the psychosocial interventions), which were assessed in a followup survey conducted approximately six months after the end of program and in particular one year after the delivery of the psychosocial interventions. A</mark> nalyses focus on exploring psychosocial mechanisms of effects on economic development, specifically women’s off-farm business development, a primary target of the program. Psychosocial variables include selfreported <mark>intrapersonal beliefs and experiences (e.g., self-efficacy, optimistic future expectations, mental health) and relational beliefs and affordances (e.g., social standing, social support, control over decision-making in the household, social norms). All measures were collected by enumerators blind to condition via in-person surveys.</mark> <mark>In Section 5, we present a pre-registered mechanism experiment (Study 3) that was embedded within the arms of the policy experiment that included psychosocial interventions (i.e. the Psychosocial and Full arms). This mechanism experiment sought to test whether independent agency and/or interdependent agency causally drove observed increases in economic development and assess associated intrapersonal and relational processes. Notably, we expanded the sample to include all program participants, regardless of their participation in the policy experiment, in a subset of 33 villages (N=2,628) and thus the mechanism and policy experiment samples were largely non-overlapping (see Fig. S1). In an individual-level experiment, we tested the effects of receiving one of two brief social-psychological interventions following the program’s community sensitization–a brief independent agency intervention grounded in selfdirection and self-advancement (“Personal Initiative”) or an interdependent agency intervention grounded in social harmony and collective advancement (“Interpersonal Initiative”). These were compared to a control condition of no additional intervention. We assess economic and psychosocial outcomes collected one year later in a follow-up endline survey.</mark> 6