The "Friends" machine-readable data file (MRDF) is a part of the larger "High School and Beyond" (HS&B) class of 1980 survey which was administered in 1980 to a national sample of over 30,000 sophomores and 28,000 seniors from 1,015 high schools throughout the United States. The "Friends" film includes data from over 58,000 respondents, all of whom identified the names of their three best friends who were also in the same school and grade as the respondent. The data file is arranged so that all students attending the same school are grouped together. Each respondent has an Identification Number (ID). The record for each respondent includes the respondent's ID and the ID numbers for those friends named by the respondent. The formal criteria for "within-range friends" were: (1) members of the HS&B sample; (2) members of the same class (sophomore or senior) as the respondent; (3) attending the same school as the respondent. All other friends were termed "not within-range friends." The order in which the three friends were named by the respondent is retained in the file. The file and the linkages among friends that it reveals can be used for tracing friendship networks and to investigate the sociometry of friendship structures (including, for example, reciprocity of choices). POPULATION: High School Sophomores (<3,800,000); High School Seniors (>3,000,000). TYPE OF SURVEY: National Survey; Sample Survey. RESPONDENTS: High School Sophomores (35,723); High School Seniors (34,981). FREQUENCY: Once. RESPONSE RATE: High School Sophomores (30,030=84%); High School Seniors (28,240=80.5%). YEAR OF FIRST DATA: 1980. YEAR OF LATEST DATA: 1980. (CDM/WTB)