A series of essays applies ideas about heredity and statistical analysis to questions of human improvement, defining the scope and aims of eugenics and outlining methods for study. The author examines proposals such as marriage restrictions, local associations, and public education, and considers relations between eugenic ideas and religion and national policy. Quantitative tools like probability theory and distribution charts are used to analyze variation in human traits. Throughout, practical limits, moral cautions, and avenues for further investigation are discussed.