When and where is Little Women set?

When the novel begins, it is Christmastime. We know the novel is set sometime during the early 1860s because Mr. March, the girls' father, is away serving as a chaplain for the North in the Civil War. When the book opens, it is likely 1861 or 1862 because it doesn't seem as though the war has been going on for very long at this point. Early in the story, while the March sisters are complaining about all the things they don't have, Jo says,

"We haven’t got Father, and shall not have him for a long time." She didn’t say "perhaps never," but each [of her sisters] silently added it, thinking of Father far away, where the fighting was.

Later, Mr. March actually sustains an injury during his service and is sent home.

As far as geographical setting, the novel takes place in New England, though the town in which the March and Lawrence families live is never explicitly named. Most readers agree the location seems to be based on Alcott's home in Concord, Massachusetts, but this is never directly stated in the story.