A harvest festival is the time each year when people celebrate having enough food gathered in to see them through to the next year. Harvest festivals of one kind or another occur all around the world, and because harvests are gathered in at different times (harvests in the Southern Hemisphere are in March, not October as in the Northern Hemisphere, for example) celebrations are in different months in different places.

In the past, harvest festivals were very important. They occurred after the harvest was gathered and the soil prepared for next year. It was the time when all work was done for the year. So they were actually later than the time the harvest was actually gathered. One example of this is American Thanksgiving, which is in November (see Thanksgiving).

In Britain, harvest festival is traditionally held on the Sunday closest to the autumn equinox (about Sept. 23). In India the festival of Holi in February–March is a harvest festival.

In Medieval times early harvest festival used to be celebrated at the beginning of the harvest season on 1 August and was called Lammas, meaning 'loaf Mass'. Farmers made loaves of bread from the fresh wheat crop and gave them to the church for use in mass, thanking God for the harvest.