This paper presents findings from a longitudinal study that examined the extent and types of challenges to curriculum in California school districts. A survey of school districts conducted in 1990 yielded 421 usable responses. The second survey, sent in 1991, elicited 379 responses, a 37.5 percent response rate. Findings indicate that the number of curriculum challenges increased by 8 percentage points. Over half of the districts reported that they had encountered curriculum challenges. The most likely reason for the challenges was religious conflict or satanic/witchcraft issues. Most of the challengers were parents who were not likely to be satisfied with the outcome of the challenge, which in most cases resulted in no change in district practices. An exception was that the challenger's child was excused from using the material. Over 40 percent of the districts reported that challenges in other districts were very disruptive, generating communitywide controversy. Nine percent of the districts reported that they would be less likely to adopt material challenged elsewhere, might not consider items known to have caused contentious challenges, or would not consider such materials. Ten tables and three figures are included. (LMI)