This paper presents the results of a study of warping (twisting) in precast concrete double tees and draws conclusions on what is being successfully done within the industry to minimize or eliminate longitudinal cracking through decks due to warping. Conclusions are given based on the results of an industry survey, an assessment of torsion parameters, theoretical calculation of cracking point, and empirical data from plant controlled testing and field experiences. Data are presented for field-topped tees and pretopped tees of various lengths and widths. Recommendations are given on the best practice to follow in controlling warping in double tees.