Noticing that many of the inmates were related by blood or marriage, he self-funded[1] a study of a family living in and around Ulster County, New York, whom he named "Jukes".
[2] Using local records and interviews he created detailed family trees and described the lives and histories of individual offenders, and then developed conclusions about what he believed were the causes of crime and dissipation.
The conclusions he drew from his study were the need for penal reform, improved public health and early childhood education and care, all indications that he supported an environmentalist position.
[2][5][6] Dugdale also noted that the Jukes were a composite of 42 families and not a single group: only 540 of his 709 subjects appeared to be related by blood,[4] and that his conclusions were tentative and inconclusive.
The collections includes correspondence, the handwritten preface to an early edition of The Jukes, and large worksheets containing raw data on over 800 individuals from which Dugdale compiled the tables for his studies.