A guide is provided to the proceedings of the Hawthorne experiments, and experimental data are now made readily available. Data from the main experiment (that in the first relay assembly test room at Western Electric) are interpreted statistically for the first time. Quantitative analysis of this quasi experiment is accomplished by time-series multiple regression using nearly five years of data. This analysis demonstrates that experimental variables account for some 90% of the variance in quantity and quality of output, both for the group and for individual workers. Imposition of managerial discipline, economic adversity, and quality of raw materials provide most explanation, obviating the need to draw upon less clearly definable human relations mechanisms. For decades the Hawthorne studies have provided a rationale for humane approaches in the organization of work by suggesting that considerate or participative treatment of workers led to better economic performance. The present analysis suggests, to the contrary, that humanitarian procedures must provide their own justification.