Purpose: The aim of this study is to examine the nature of interdisciplinary thinking and the conditions and processes that foster it amongst first year undergraduate students. Methodology: This study with 510 Australian students drawn from two cohorts explored an initiative to promote interdisciplinary teaching in an undergraduate ethics-based subject. The study focused on a case study-based reflective essay intervention to compare the teaching and learning outcomes in the two student cohorts. Findings: The results show how a case study-based reflective essay intervention impacted on interdisciplinary learning. Introducing the case-study-based reflective essay improved interdisciplinary thinking. Findings show that integral to engaging students in interdisciplinary learning is a need for more experiential and active approaches built into education itself. Research limitations/implications: The study findings extend Spelt et al.'s (2009) model in the business education context to link student learning outcomes to the learning processes, learning environment and interdisciplinary thinking. A key limitation of this study is that the intervention is limited to only two student cohorts. Practical implications: The study recommends the use of reflective practice in interdisciplinary subjects to support a variety of learning outcomes across disciplines including classroom-based and assignment-based reflective practices which influence interdisciplinary thinking and active learning. Originality/value: There is limited understanding on how business schools should or could attempt to promote interdisciplinary teaching and the actual methods for doing so. This study highlights the significance of integrating reflective practice in undergraduate business education to promote students' interdisciplinary thinking.