The literature on strategy practice as a historically embedded phenomenon is scant. To fill this gap, this study expands the strategy-as-practice (SAP) literature by examining the meaning of historical embeddedness in the evolution of strategy practice. We draw on the framework of strategic planning as a social practice presented by Langley and Lusiani (2015) and the notion of modus operandi (Chia & Holt, 2006). We use a longitudinal case study design combined with historical methods to examine the evolving and historically embedded strategic planning practice of a healthcare organization throughout its lifespan. Our results show that historical embeddedness appears in structures and routines, materiality, positioning, and reflecting, representing an internalized way of acting. We show that reflection is essential for the evolution of strategy practice and contribute to theory development by demonstrating that strategic planning is a continuous development process and that, in this evolution, history provides continuity yet also facilitates the evolutionary process. Keywords: Evolution; historical embeddedness; strategic planning; strategy-as-practice