<p>Although nearly all unitary states have institutionalized local government systems, the timing and degree of decentralization at their inception vary considerably. To explain these differences, this paper develops an actor-centered theory that integrates the historical institutionalist perspective and confirms its validity in six cases. The primary conclusion is that the timing of the institutionalization of local government systems and the degree of decentralization within these systems vary depending on two factors: decision-makers’ instrumental beliefs about the value of local autonomy on the basis of their prior experience in autonomous local organizations and the occurrence of a political crisis. When all or no decision-makers hold such instrumental beliefs about the value of local autonomy, a local government system is institutionalized mainly through constitutional enactment, with variable degrees of decentralization. When there is conflict between decision-makers with and without such instrumental beliefs, the former group capitalizes on the emergence of a political crisis to introduce a highly decentralized system preceding constitutional enactment. This study contributes by analyzing the apparent paradox of the concurrent occurrence of decentralization and national integration through centralization and by presenting a comprehensive cross-national analysis of initial local government systems.</p>