In a central region of northern New Jersey, remote from any direct line of travel, lies a town named for one of the families connected with the earliest settlement of the colony. This family rose to distinction in many of its branches, but honors itself chiefly for having produced one of the most brilliant advocates of the cause of Independence of which New Jersey can boast. He was descended on his mother’s side from the first president of Princeton University and took his degree there before he was sixteen years of age. From this family, Martin Kallikak’s youngest son, Joseph, chose his wife. It is interesting to note that the descendants of this pair have shown a marked tendency toward professional careers. One daughter, however, married a farmer, and most of her descendants have remained fixed to the soil. Another daughter married a prominent merchant, and this line, having been fixed in the city, has produced men chiefly engaged in mercantile pursuits; but the sons, of whom there were five, all studied medicine, and although only one of these became a practicing physician, their children have carried on the family tradition in this line. On the outskirts of another New Jersey town, in a beautiful old homestead, inherited from his mother, lives a grandson of Frederick Kallikak, oldest son of Martin. He is a courteous, scholarly man of the old school. His home is rendered particularly attractive by the presence of his southern wife and two charming daughters. In his possession are numerous articles belonging to his great-grandfather. This gentleman manifested such an intelligent interest in giving information in regard to his family that it seemed a question of honor to inform him as to the purpose of the investigation, laying bare the facts set forth in this book. He proved to be, perhaps, the one man best qualified in the entire family for entering into an analysis of its characteristics, and this he did freely, in so far as it would serve the ends of the investigation. Another descendant of Martin Kallikak Sr., a granddaughter of his youngest child, Abbie, had been previously informed regarding the same facts. This lady is a person not only of refinement and culture but is the author of two scholarly genealogical works. She has, for years, been collecting material for a similar study of the Kallikak family. This material she generously submitted to the use of the field worker. In the end she spent an entire day in the completion and revision of the normal chart presented in this book. No praise can be too high for such disinterested self-forgetfulness in the face of an urgent public need. We owe to these two persons most of the information which has made possible the study of the normal side of this family.