The primary objectives of this project were to determine which species of Crotalaria (Fabaceae) occur in Alabama and the county distribution of each species. Crotalaria, known commonly as rattlebox, is recognized as consisting of seven species in Alabama. The most common species are Crotalaria sagittalis, C. rotundifolia, and C. spectabilis. The less common species are C. purshii, C. lanceolata, C. pallida, and C. ochroleuca. In Alabama, introduced species of Crotalaria (C. lanceolata, C. ochroleuca, C. pallida, and C. spectabilis) generally have showier inflorescences and reach greater maximum heights than native species (C. purshii, C. rotundifolia, and C. sagittalis). The dichotomous key and descriptions we present are modifications from earlier authors; however, all measurements are based on morphological features of the vegetative and reproductive structures of the more than 460 specimens studied during this project. Data for the county-level distribution maps were compiled entirely from herbarium vouchers.