To conduct comprehensive treatment effectiveness studies, evaluators m
ust frequently track, locate and interview service recipients long aft
er program participation has ended. For some populations, this is an a
rduous task. But, despite wide variations in retention rates, the publ
ished literature from follow-up studies rarely provides information on
their tracking, locating, or interviewing techniques. The present rep
ort concerns a 12-month follow-up study of individuals who were homele
ss and mentally ill, which achieved a remarkably high retention rate-o
ver 70%. Quantitative information is presented on client characteristi
cs related to locatability and agreement to be interviewed, as well as
qualitative information on successful techniques, from a focus group
session with research interviewers.