Of the more than 2,200 participants in the survey, 67 percent said the major reason they use social networks is to stay in touch with current friends, 64 percent to stay in touch with family members and 50 percent to connect with old friends they had lost touch with.
Other major reasons for joining a social network were connecting to others with shared hobbies or interests (14 percent), making new friends (9 percent), reading comments by celebrities, athletes or politicians (5 percent) and finding potential romantic or dating partners (3 percent).
Researchers also discovered that survey participants under the age of 50 were more likely to cite staying in touch with current friends (more than 70 percent) and connecting with old friends (more than 53 percent) as a major reason for joining a social network.
According to Pew, looking for new friends is not a major consideration among most social networkers. Only 9 percent chose it as a major reason for using social networks, and 57 percent said it wasn't a consideration at all.
Middle-aged adults are more interested in using social networks for hobbies and interests than other age groups, the report said, with 16 percent of 30- to 49-year-olds and 18 percent of 50- to 64-year-olds picking that as a major reason for joining a social network.
While connecting with public figures and celebrities didn't garner many responses as a major reason for joining a social network, some ethnic groups, African-Americans (10 percent) and Latinos (11 percent), did cite it as a major reason for using a social network. That compares to 3 percent for whites, the researchers found.
Follow freelance technology writer John P. Mello Jr. and Today@PCWorld on Twitter.