Using ‘simple rules’ may enable managers to take organizational decisions more rapidly. While prior research presents advantages of simple rule use during strategy formation, we lack insights into how firms can deliberately create simple rules and mitigate the challenges during strategy implementation. This is particularly interesting for established firms struggling to leverage their wealth of experience. We explore how managers of a multinational corporation deliberately create and use simple rules to implement the firm's growth strategy. Drawing on interviews and secondary data, we reveal the activities through which managers ensure the relevance and legitimacy of codified simple rules, yet also establish causality between simple rules and outcomes. Simple rule creation is accomplished via bottom-up identification and lateral validation, its use via consistent top-down guiding and timely adaptation. Our findings contribute to the growing body of research on the evolution of simple rules and aspects of strategy implementation more generally.