Parsva Ekadashi, also known as Parsva Parivartini Ekadasi or Vamana Ekadashi is observed on the eleventh day during Shukla Paksha inBhadrapad month. In 2015, Parshva Parivartini Ekadashi date is September 24.
Devotees of Lord Vishnu believe that on this Ekadasi day Vishnu who reclines on Aadisesha turns to another side. This turn is called as Parivarthan.
Parshva Ekadashi is one of the Ekadashi vratas that falls during Chaturmas period. Parivartini Ekadashi is also called as Vamana Ekadashi because on this Ekadasi Lord Vamanasent King Mahabali to Pathala loka.
Vamana Jayanthi is observed on the next day to Vamana Ekadashi. The legend of Parsva Parivarthana Ekadashi is mentioned in Brahma Vivarta Purana as the conversation between Lord Sri Krishna and Yudhistira.