It has been a decade since the Prime Minister’s Science, Engineering and Innovation Council (2009) recommended that programs and resources be developed that take advantage of the sensitive periods for developing skills, preparing young children for formal education. More recently, a Grattan Institute report called for policy reforms recommending that: all teachers be provided with practical tools as well as evidence-based techniques and strategies to create a learning climate and to identify triggers for student disengagement, so they can adapt and improve their approaches (Goss & Sonnemann, 2017). ‘Student engagement’ has also recently been positioned as an important outcome in the newly developed Australian school performance framework (Commonwealth of Australia, 2018, p. 4.12). Engagement matters because when students are engaged in class, they learn more (Goss & Sonnemann, 2017). In response to these recommendations, this study explored student engagement and curiosity, the indicators of interest, by designing an enrichment program for the early years. The enrichment program was based on an educational, biological and psychological rationale. Montessori's Philosophy of Education and Vygotsky's Social Development Theory provided a constructivist educational perspective on learning and a framework for developing the enrichment program. From the biological perspective it focussed on the early years when young brains are primed for learning with synaptic formation in the prefrontal cortex at its highest and young children in the sensitive period for language development. From a psychological perspective, the multiple-intelligences model (Gardner, 1983/2011) provided a holistic view of the enrichment response and the program curriculum. A broad-based, content-rich curriculum was delivered via an intentional–constructivist teaching approach. Over a period of three years, four-and five-year old children in a pre-preparatory classroom undertook the enrichment program. The outcomes of this research were derived from three types of data: questionnaires and tests; observations made from video recordings and photos; and teacher talk. After three comprehensive cycles of the design-based research process the enrichment program was designed, evaluated, refined and redesigned. Factors impacting interest as indicated by engagement (behavioural, emotional and cognitive) and curiosity were identified and the process of interest development within the program was explored. It was evident that a range of factors had an impact on engagement and curiosity, providing III strategies and evidence-based techniques, most of which could be leveraged to enhance interest. Exploring the process of interest development in the program revealed that interest was integral to learning and a key factor in creating a learning culture. The strength of this research lies in identifying and consolidating the many factors impacting interest, and incorporating insights into an enrichment program, a practical manifestation of the research. The research was also able to conceptualise the process of interest development in an enrichment program addressing an identified gap in early childhood education. Recommendations associated with practice, policy as well as recommendations regarding future research initiatives emerged from the findings. This research provides a foundational step to enhancing early childhood teaching practices that aim to take advantage of the learning potential of young children.