Ghana subscribed to the global target of reaching at least 50% of exclusive breastfeeding in the first six months of birth by the year 2030. Policies and programmes to promote exclusive breastfeeding have been formulated and implemented in the country. In spite of these efforts, existing evidence showed that the rate of exclusive breastfeeding in the first six months post-delivery has been declining over the past decade. It was therefore important to understand behavioural factors that influence exclusive breastfeeding among teenage-mothers and propose a behavioural conceptual model based on the understanding of exclusive breastfeeding from the perspective of the teenage-mothers and their social environments. The study was conducted in three phases using multistrand mixed methods within the pragmatism philosophical framework. The Theory of Planned Behaviour and the six steps framework for developing models to address public health issues were used as frameworks in the study. In the first phase, the researcher used qualitative exploratory descriptive design to gain an understanding of the behavioural determinants of exclusive breastfeeding from the perspective of teenagers aged between 13 - 19 years attending antenatal care services at public facilities. Data were generated through focus group discussions and analysed using Group-level thematic and content analysis. In the second phase, longitudinal descriptive correlational designs were used to establish the relationships between the exclusive breastfeeding intentions during the prenatal period and actual breastfeeding practices at six months post-delivery. Structured questionnaires were used to collect data during the last visit of antenatal care visits and six months post-delivery. Data generated were analysed through descriptive inferential statistics. In the last phase, the researcher used meta-inferences to identify the key concepts of conceptual model from the integrated qualitative and quantitative results. Theoretical triangulations were used to define and establish relationships between the concepts and to structure the conceptual model. The integrated results of the two phases of the study showed that exclusive breastfeeding practices among teenage-mothers within the social context of Ghana are determined by certain personal and social related behavioural factors. The approval of the exclusive breastfeeding practice by the teenagers’ mothers and nurses/midwives’ capabilities to provide effective breastfeeding education were the strongest determinants of exclusive breastfeeding up to six months among teenage-mothers in Ghana. From these results, the researcher proposed an integrated behavioural conceptual model that provides an understanding of exclusive breastfeeding practice and the process of promoting exclusive breastfeeding among teenage-mothers in the social context of Ghana. The findings of this study have implications for public health policy-makers, health services managers, health sciences education and further research. / Health Studies / D. Lit. et Phil. (Health Studies)