The aims of this study were to (a) qualitatively determine former students' perceptions of environment, personal and behaviour factor changes that were due to the teachers involved in the Strengthening of Mathematics and Science in Secondary Education (SMASSE) project in Kenya and (b) reveal the long-term influence of these qualitative changes on their lives. The study also clarified the significance of using life story analysis to this end. The theoretical framework we utilised is social learning theory. Data collected from interviews were examined using Steps for Coding and Theorisation (SCAT) analysis, as well as NVivo, to identify respondents' experiences as former SMASSE students. First, SCAT analysis revealed that participants' lives were influenced in the long term owing to changes in: (a) environmental factors, such as interaction with SMASSE teachers and collaboration with other students; (b) personal factors, such as changes in cognitive and affective aspects; (c) behavioural factors, such as learning methods. Second, by using NVivo to integrate all the stories, we showed that former students' perceptions of the environmental, personal and behaviour changes that were due to the teachers involved the SMASSE project were mutually interrelated. The analysis has also identified long-term effects on various aspects of human resource development: post-graduation career development, employment opportunities, and mindset. Finally, the results of this study emphasise the robustness of qualitative research in identifying the qualitative changes in the participants in a multi-dimensional manner for this international project.