The development of a mechanistically based model (CRACK) that predicts the spacing of cracks in roller-compacted concrete (RCC) pavements due to restraint of drying shrinkage and thermal contraction is presented. The model considers the RCC pavement thickness, paving lane length, base friction characteristics, climatic time-temperature regimes, as well as the RCC drying shrinkage, coefficient of thermal contraction, strength gain, and modulus of elasticity. The model also determines the tensile stresses and displacements of the RCC slab along its length, from which the crack width is predicted. The CRACK program was used to predict the crack spacing and width at four RCC pavement field sites, and the predicted results were compared with field measurements. The model tends to overpredict the observed crack spacings, in part because of the simplifying assumptions used in the model development and the fact that the model does not consider fatigue stresses from warping, curling, or traffic-related loads, which cause additional cracking. However, the predicted crack spacing provides a basis for selecting joint spacings, and the predicted crack widths may help in the design of joint sealant reservoirs.