Mohini Ekadashi occurs during the waxing phase of moon in the month of Vaisakha (April – May). The greatness of this Ekadasi was explained by Vasistha to Lord Ram; also Lord Krishna narrated it to Yudishitira, the eldest of the Pandavas. In 2013, the date of Mohini Ekadasi is May 21.
Sage Vasishta talks about this Ekadasi to Lord Ram who approaches the Sage with a heavy heart after his separation from Sita. Sage Vasishta suggests to Lord Ram he will be able to over the sadness and remorse by observing Mohini Ekadasi. As it will help him to overcome ignorance and distress created by Maya. The sage also says that the Ekadasi helps in removing the burden of sins.
It is said that the fasting on Mohini Ekadasi is better than bathing in holy in rivers and performing sacrifices.