Scholars have long assumed that Spanish colonial rule had only a limited demographic impact on the Philippines. Filipinos, they believed, had acquired immunity to Old World diseases prior to Spanish arrival; conquest was thought to have been more benignt han what took place in the Americas because of more enlightened colonial policies introduced by Philip II. This book illuminates the demographic history of the Spanish Philippines in the sixteenth and seventeenth centuries and, in the process, challenges these assumptions. The book demonstrates that the islands suffered a significant population decline in the early colonial period. It argues that the sparse population of the islands meant that Old World diseases could not become endemic in pre-Spanish times, and also shows that the initial conquest of the Philippines was far bloodier than has often been supposed. Comparisons are made with the impact of Spanish colonial rule in the Americas. The book examines critically each major area in Luzon and the Visayas in turn. It proposes a new estimate for the population of the Visayas and Luzon of 1.57 million in 1565 and calculates that by the mid-seventeenth century this figure may have fallen by about two-thidrs.