Adults caught up in the coloring book craze now have new and more social ways to participate: through libraries and meetup groups.

Libraries are holding adult coloring programs more and more in response to the spike in interest, according to the American Library Association. Cities with events include New York City, Denver and Milwaukee. Gatherings are also popping up through Meetup.com.

Jane Henze, the adult programing director at DeForest Public Library near Madison, Wisconsin, started the library's free program this summer. They now do it twice a month, with between 11 and 16 people.

Full of intricate designs, the books are touted as a way to reduce stress and anxiety. This month, coloring books took up the top 10 spots on the New York Times best-selling list of games and activities, up from nine in December.