Historical research on Chilean population has been thwarted for some time by intractable sources and rudimentary methods. Nevertheless, within the past two decades researchers have begun to achieve some successes. Attention has turned from simply ascertaining gross population totals and growth rates to a much wider range of topics. Significant examples include: the relationship between population growth, illegitimacy, vagrancy, and labor supply; the social context of marriage, family formation, and kin ties; the nature, frequency, and intensity of mortality crises; demographic responses to population pressure; the social and economic repercussions of European immigration; and the determinants and consequences of rapid growth and redistribution of population in the twentieth century (Góngora, 1965; Bauer, 1975; Hurtado, 1966; Solberg, 1969; Young, 1974; Sadie, 1969). To study these topics satisfactorily we must both maintain the healthy skepticism of our distant precursors (e.g., Barros Arana, 1880–1900; Palacios, 1904; and Vergara L., 1900) and integrate the demographer's analytical tools with the historian's skill in finding, selecting, and interpreting a whole range of quantitative and qualitative documents. Demographers have demonstrated that even post-1920 data collected by the Chilean Statistical Bureau have substantial and varying degrees of error, notwithstanding the considerable advances in data collection techniques, improvements in the educational levels of the population, and economic inducements to insure the public's cooperation (Somoza and Tacla, 1969; Gutiérrez, 1969). In the not too distant past, civil administrators and priests received crude, if any, instructions, administered several hundred square kilometers of poorly defined territory, and faced an almost insurmountable task of enticing information from a widely dispersed, highly mobile, poor, and uneducated populus. Consequently, historical studies with exclusively demographic ends, using narrowly defined data bases and relying principally on arithmetical or statistical techniques, may prove to be extremely frustrating to carry out and somewhat barren in their findings. Attempts to replicate European studies with Chilean materials, whether simple aggregations of annual totals or tediously reconstructed family life histories, will run a high risk of failure unless researchers incorporate broader questions of social history, exploit an extensive range of documentation, and integrate historical, demographic, and statistical reasoning. While little mathematical sophistication may be necessary—elementary measures may prove the most powerful—a mature, sensitive understanding of the logic of these disciplines, which comes only with considerable study and experience, is essential. The slavish application of demographic formulae and the invention of ill-considered measures are direct pathways to embarrassing nonsense.