Prime Minister Narendra Modi will lead the celebrations by participating in a mass demonstration of Common Yoga Protocol here on the day.
The 45-minute rehearsals began at 7:30 am and was attended by defense forces, ITBP personnel, Panjab University students, Divyangs, yoga foundations, school children and a select few from yoga orientation training camps.
For the main event, the emphasis this year will be on participation of Divyangs, the nomenclature coined by Modi for differently-abled, youths and people from economically weaker sections.
While the main event will begin at 6.30 am the Common Yoga Protocol will begin at 7 am and last for 45 minutes, the release said.
Also Read
Over 173 Indian missions across the world are also organising Yoga demonstrations to spread awareness about IDY, the statement said. Several missions organised a series of curtain raisers in various parts of the world, it said.
Today's rehearsal was presided over by Haryana and Punjab Governor Kaptan Singh Solanki and AYUSH Ministry secretary, Ajit M Sharan, an official statement said.
The main IDY event will witness participation of nearly 35,000 people at the Capitol Complex and 10,000 persons at 100 other locations across the city.
It will be broadcast live by Doordarshan and All India Radio.
The event will be celebrated at seven different locations in the national capital, including Connaught Place, which will host the largest gathering of approximately 10,000 people.
An official statement said reputed Yoga institutions will participate by leading the functions across the country.
Demonstrations will also be organised at several places in the state capitals and all district headquarters.
In the National Capital Territory of Delhi, the major event being organised by AYUSH Ministry and New Delhi Municipal Council (NDMC) will be at Connaught Place, Lodhi Garden, Nehru Park and Talkatora Garden.
Union Minister for Urban Development, Venkaiah Naidu, Lt Governor of Delhi Najeeb Jung and MP Meenakashi Lekhi will be present at events in Delhi.
The HRD Ministry has taken up the initiative of conducting 'Yoga Olympiad' with participation of children from government schools.
The first IDY was organised successfully in India and the world last year, after United Nations General Assembly, in December 2014, declared 21st of June as International Day of Yoga.