Empirical support for institutional influences on public service motivation (PSM) has been growing in recent years. Yet, we lack a concept and a measure that captures the capacity of public institutions to energise and propel members to perform meaningful public service and pursue the common good. This study aims to address this gap by presenting a conceptual foundation of institutional PSM. By extending PSM from the individual to the institutional level, we lay the groundwork for a fundamentally different approach to PSM measurement. We draw upon multiple theories and empirical studies to propose that institutional PSM consists of four pillars: public-service orientation, legitimacy, merit, and support. We then present research propositions for studying institutional PSM.