Skid resistance is one of the important serviceability indicators related to safety on wet pavements. There is a need to manage skid resistance systematically to maintain the level of safety performance of roadway surfaces. This study focused on the development of a skid resistance deterioration model based on the analysis of skid data inventory collected in California. The California Department of Transportation (Caltrans) has collected skid resistance data across the complete state highway network over the past two decades using a standard locked-wheel skid trailer, ASTM E-274. This study utilizes skid data collected on more than 300 miles of asphalt concrete freeway in California over a period of twenty years. Most of the possible factors found in previous studies to influence skid resistance were considered. Panel data parameter estimation methods were used. The results indicate that factors with the largest effects on skid resistance are the age of pavement, ADT, temperature, precipitation, and the length of the period since the last significant precipitation.