Dev Diwali is observed on the full moon day (Purnima) in the month of Kartik in a traditional Hindu calendar and is the Diwali of the Devas or Gods. Dev Diwali 2015 date is November 25 and it is an important festival in Gujarat and other parts of
North India. Tulsi Vivah ritual comes to end on the day.
Please note that in some regions Dev Diwali is observed on the first day of Margashirsh month especially in Maharashtra.
Dev Diwali also marks the end of the Diwali celebrations. An important ritual on the day is the lighting of Diyas (lamps) after the sighting of the moon.
Legend has it that Lord Vishnu returned to Vaikunta, his abode, on this day after the Vamana incarnation and visiting King Bali.
Another legend has it that Lord Shiva killed three demons, who spreading Adharma and killing innocent people, and destroyed the three cities built by the demons on Dev Diwali day. Therefore the day is also known as Tripurari Purnima.