Core Concept: We often wonder why making friends as an adult feels so difficult. It turns out, there is an exact timeline for friendship development. Research demonstrates that it takes about 50 hours of shared time to move from acquaintance to casual friend, 90 hours to become standard friends, and over 200 hours to become close friends.

• Original Citation: Hall, J. A. (2018). How many hours does it take to make a friend? Journal of Social and Personal Relationships, 36(4), 1278–1296.
• Link: https://doi.org/10.1177/0265407518761225