The Conference on Demography of Incomplete Data: Own Children Methodology, Past and Present was organized by the Northeast Asia Economic Forum (NEAEF) in collaboration with the East-West Center and the College of Social Sciences of the University of Hawai‘i at Mānoa, in Honolulu, Hawai‘i, on 2 July 2018, in view of continuing and expanding activities in the use of the methodology in new areas such as the European countries as well as in historical demography. The own-children methodology for estimating fertility has a long history going back to the 1960s and has been applied in an increasing number of countries and areas globally for which the census and survey data are available. In assessing the methodological paper "The Own-Children Approach to Fertility Estimation: An Elaboration," by Lee-Jay Cho, the United Nations Manual X: Indirect Techniques for Demographic Estimation stated that "probably the greatest innovation introduced by the proponents of the own-children method is the exploitation of seldom-used census information for fertility estimation purposes." In the course of the numerous applications beginning with the United States for the countries of East and Southeast Asia and the Pacific, such as Korea, Japan, China, Malaysia, and Indonesia, the own-children method was extended, improved, and elaborated by demographers at the East-West Population Institute (EWPI), and in 1987 resulted in the publication of a long-enduring volume The Own-Children Method of Fertility Estimation by Lee-Jay Cho, Robert Retherford, and Minja Choe. Subsequent methodological extensions and refinements were made possible with Norman Luther and others. The Conference highlighted historical background, expanding applications, and most recent developments in the own-children methodology, and at the same time celebrated the success and sustainability of the methodology achieved by the contributions of those dedicated demographers cited in this proceedings volume.