The objective of this paper is to determine the extent to which adopting Nonaka's SECI knowledge-creation processes enhances strategic planning capacity in the context of Hong Kong school education. A quantitative questionnaire survey is conducted to examine the predictive effects of the knowledge-creation processes of the SECI model on strategic planning processes. Data is collected from 42 principals and 392 teachers from 42 schools. A multilevel structural equation model is applied to examine the predictive effects of the mechanism on strategic planning capacity. Results show that the combination process of the SECI knowledge-creation model predicts strategic planning capacity, while a collaborative culture enables the process of knowledge externalization and combination. In response to the international debate on culture and context-dependent issues in using Nonaka's SECI model for knowledge creation, this study reaffirms that the SECI model is largely dependent on Japanese collaborative culture. The study also brings theories of knowledge management into discussion of strategic management in the school context. To enhance school planning capacity, school leaders should cultivate a collaborative culture to support the alignment of different departments in the knowledge combination process to craft strategies for development planning.