In sub-Saharan Africa (SSA), social and economic interactions are governed by both formal (statutory laws, policies, and regulations) and informal institutions (customary laws, social expectations, and religious tenets). When customary and statutory laws misalign, when regressive customary laws are enforced, or when statutory laws are weakly enforced, marginalized groups including children, women, and those impacted by HIV become especially susceptible to economic disenfranchisement predominantly through the misappropriation and loss of household assets. Asset-building interventions working with these groups in the region have shown tremendous success, and whereas they recognize the crucial role formal institutions play in asset accumulation, they are yet to integrate components that address the sociocultural barriers to economic enfranchisement. This paper identifies the ways through which vulnerable groups are susceptible to wealth loss and the ways in which formal and informal rules intersect to restrict property rights. This is followed by an analysis of the informal institutional constraints placed on vulnerable groups in SSA in asset accumulation. Finally, programmatic interventions are proposed that if implemented would increase the capacity of asset-building programs to strengthen the economic functioning of vulnerable groups.