School principals' interpretation of the context for their work has significant implications for their practice and for organisational theory educational settings. Principals' sense-making capability can change over time, as in all adults. Sense-making capability is grounded in adult ego development (AED) theory which describes eight distinct stages of development. The research reported here assessed the AED stage of 13 school principals in England using the Washington University Sentence Completion Test and using critical incident technique analysed their sense-making capabilities and how others experience them. The analysis of the school principal case studies indicate substantive differences between those in different stages of AED in: their awareness of and sensitivity to organisational complexity; how they interpret the role of others in significant events/incidents; and how they are experienced by others.