The exceptionality of the skills of calendrical savants and the role of practice were investigated. Experiment 1 compared four autistic calendrical savants to Professor Conway, a distinguished mathematician with calendrical skills. Professor Conway answered questions over a greater range of years but some savants knew more calendrical regularities. Experiment 2 studied the development of a calendrical savant's ability to answer date questions for very remote future years. He started by making written calculations and progressed to mental calculation. His variation in response time for remote dates was similar to that for near dates. The findings are consistent with the view that calendrical savants develop their skills through practice.