Student performance in general organic chemistry courses is determined by a wide range of factors including cognitive ability, motivation and cultural capital. Previous work on cognitive factors has tended to focus on specific areas rather than exploring performance across all problem types and cognitive skills. In this study, we have categorized the different kinds of problems encountered in general organic chemistry, and correlated performance in each problem type with overall class performance. Fairly reproducible results are found for ten consecutive semesters over five academic years. Problem types that require higher-level cognitive skills tend to correlate better with overall class performance than those that rely more heavily on memorization. Performance on some problem types was found to predict up to [similar] 90% of the variances of overall class performance. Correlations across problem types with external student characteristics, such as general chemistry grade, are interpreted as highlighting the important contributions of other factors in addition to cognitive ability to success in organic chemistry.