This book is the first comprehensive study of the Vedic present formations with the suffix ya (' ya-presents' for short), including both present passives with the accented suffix ya and non-passive -ya-presents with the accent on the root (class IV in the Indian tradition). It offers a complete survey of all ya-presents attested in the Vedic corpus. The main issue in the spotlight of this monograph is the relationship between form (accent placement, diathesis) and function (passive/non-passive) in the system of the -ya-presents - one of the most solidly attested present classes in Sanskrit. One of the aims of the present study is to corroborate the systematic correlation between accent placement and the passive/non-passive distinction: passives bear the accent on the suffix, while non-passives have the accent on the root. The book also focuses on the position of the passive within the system of voices and valency-changing categories in Old Indo-Aryan.