Assam is a land of fairs and festivals. Most of the festivals celebrated in Assam characterize the spirit of accommodation and togetherness in the diverse faith and belief of her inhabitants. This perfect fusion of heritage of her numerous races has made Assam the home of the most colorful festivals reflecting the true spirit, tradition and lifestlye of the people of Assam.
The major festivals celebrated in Assam are Bihu, Baishagu, Ali-Ai-Ligang, Baikho, Rongker, Rajini Gabra Harni Gabra, Bohaggiyo Bishu, Ambubashi Mela and Jonbill Mela and so on. 
The people of Assam also celebrate Holi, Durga Puja, Diwali, Swaraswati Puja, Lakshmi Puja, Kali Puja, Idd, Muharram, Me-Dam-Me-Phi, the birth and death anniversaries of Vaishnava Saints Srimanta Sankardev and Madhabdev. The tribals of Assam have their own colourful festivals like the Kherai Puja of the Bodos, the Baikhu and Pharkantis of the Rabhas, Ali-ai-ligang and Parag of the Mishing tribe, the Sagra-misawa wansawa and laghun of the Tiwas.
Bihu is the most important festival of Assam. It is celebrated with joy and abundance by all Assamese people irrespective of caste, creed, religion, faith and belief.
Three Bihus are celebrated in a year: Bohag Bihu which augurs the wish for a good harvest because this is the time when farmers start sowing, Kaati Bihu which is observed to mark the cutting and binding of grains and Magh Bihu which marks the season of harvesting of grains.
The most important Ahom festival which deserves mention is the Me-Dum-Me-Phi, i.e., the ancestor worship festival which is observed by the whole Ahom community. This is performed annually on the 31st of January and helps to develop social contacts and community feelings among the Ahoms. Colourful processions with devotees in traditional finery are also taken out on the occasion. It is believed that if Me-Dum-Me-Fi is not celebrated in the customary way, the deities will be displeased and consequently there will be crisis in the State like political rivalry and infighting, increased activities of militancy, natural upheavals like floods and earthquakes resulting in loss of human lives and property. Therefore, performance of Me-Dum-Me-Fi is a must in the interest of overall well-being of the people and the society.
This festival is celebrated in Assam with much pomp and enthusiasm. 
This festival is commonly celebrated by the tribe of 'Boro Kacharis' of Assam and it is the famous festival of the Boros. Famous for its myriad colours and merriment, 'Baishagu' is generally celebrated by the Bodo Kacharis during mid April. It is the most cherished festival of the Bodo tribe. The Bodos also celebrate it as a springtime festival at the advent of the new year. In this festival of Baishagu many traditional musical instruments are used. Such music instruments are: Khawbang, Jotha, Gogona, Siphung, Kham etc. At the end of this Baishagu Festival of Assam the Assamese people gather together in a specified place for a community prayer which is called as "Garjasali" in Assamese language.
Is the most important festival of Kamakhya temple of Guwahati and is held every year during monsoon (mid-June). 
It is a ritual of austerities celebrated with 'Tantric rites'.During Ambubashi the doors of the temple remain closed for three days. It is believed that the earth becomes impure for three days. During this time no farming work is undertaken. Ambubachi mela is held at the Kamakhya temple, after being closed for the afore-mentioned three days. On the fourth day only the devotees are allowed to enter inside the temple for worship. Thousands of devotees from all over the country and abroad visit this mela.