This thesis is about psychological constructions underpinning intentional action to improve well-being by people in a neighbourhood on the urban fringe of Bamako, Mali. There is a large deficit in the theorisation of psychological elements of agency and empowerment in the development literature. Instead empowerment is generally defined as a favourable opportunity structure, as choice or as the distribution of power. Further still, the examination of the psychological literature reveals a lack of empirical research related to non-Western contexts and development policy. In view of this, I present the results of an empirical study using the inductive mixed methods to examine the central factors contributing to initiatives people undertake to improve personal and collective well-being. Informants articulated that the psychological concepts of dusu (internal motivation) and ka da I yèrè la (self-efficacy) were most important to their purposeful agency. The empirical analysis is divided into three parts and based primarily on qualitative data, enriched by quantitative analysis. Firstly I will examine the concepts of dusu and ka da I yèrè la, which are characterised as having an instrumental and intrinsic significance to people’s purposeful agency. They were also characterised as important factors in supporting local social development initiatives. Secondly, I will show how these psychological concepts were not related to the agent’s socio-economic characteristics or decision making ability, rendering both variables weak proxies for measuring psychological agency. Instead I found that measures of intrinsic motivation and self-efficacy are more viable for evaluating psychological agency. Thirdly, however, whilst dusu and ka da I yèrè la are important to people’s agency and the social development of the neighbourhood, they cannot be viewed as a silver bullet to social development in Kalabankoro Nerekoro. Specifically, in the examination of collective purposeful agency in group work (associations), the functioning of groups is impacted by the internal dynamics within the group, causing sometimes breakdown of the group. Further still, gender and age norms as well as capability deprivation and conflicting world views all thwart the ability of associations to achieve their goals. I underline that agents cannot always succeed in the pursuit of their well-being goals, even though they demonstrate high levels of psychological agency unless structural inequality at the micro, meso and macro levels of Malian society are addressed. Through this empirical study, this thesis will contribute the closing of the gap between psychological and development literatures as well as work towards developing measures of psychological agency.