In domestic horses, many aspects of stereotypic behavior are still under question. Social, housing and feeding conditions, as well as genetic predispositions, seem to be involved – but little is still known about the determinants of the type of stereotypy performed, nor about the potential correlates of such behaviours with reproduction, cognitive abilities or working conditions. These issues will be addressed here via two complementary studies, one on breeding mares, the other on working horses, both involving large samples of animals living in the same conditions and with limited genetic variability (one breed in each case). These studies reveal 1) a clear relation between reproductive success and the occurrence of stereotypies (lower conception rates in stereotypic mares), and a relation between reproductive status (barren, maiden or with foal) and the occurrence and type of stereotypies; 2) relations between cognitive performance and stereotypies (lower learning in stereotypic horses), and between the type of work usually performed and the occurrence and types of stereotypies performed when animals were stabled. The types of stereotypies observed also differed greatly between these two studies. These datasets raise further lines of discussion on the physiological, emotional and motor correlates of these abnormal behaviours.