The primary purpose of this study was to develop criteria to improve the effectiveness of Utah's flexible pavement crack sealing practice. The methodology involved field measurements of seasonal variation in crack width and in-depth interviews of Department members at various levels of management in maintenance, materials, construction, and research. Other states were queried by questionnaire in order to obtain a comparative base on with to evaluate Utah's practice. Findings indicate that flexible pavement cracking is a significant problem in the Far West, Rocky Mountains, Great Lakes, and New England. Criteria to determine when to seal (fill) cracks, and materials or techniques to be used vary widely. Choice of materials if affected by storage requirements and equipment available. Prepackaging of materials especially designed for crack sealing has resulted in improvements in control of mix and material properties; further gains can be anticipated as mix design improves and material specifications become more exact.. Low temperature and freeze thaw cycles significantly affect the amount of thermal cracking and the performance of crack sealant. Poor rideability, increased pavement deterioration, obscured traffic markings, lowered skid resistance can result from inappropriate selection and installation of crack sealants. Ductile sealants such as Crumb rubber/asphalt cement mixes, in combination with routing appear to offer substantial gains in sealant life and performance. These gains are partially offset by increased installation cost and hazard to the operator. Existing data is insufficient for benefit/cost analysis.