This experiment investigated the effect of small-group versus individual hearing loss prevention (HLP) training on the attenuation performance of passive insert-type hearing protection devices (HPDs). A subject-fit (SF) methodology, which gave naive listeners access only to the instructions printed on the HPD product label, was used to determine real-ear attenuation at threshold (REAT) at third-octave noise bands between 125-8000 Hz. REAT measurements were augmented by use of the Hearing Loss Prevention Attitude-Belief (HLPAB) survey, a field-tested self-assessment tool developed by the National Institute for Occupational Safety and Health (NIOSH). Participants were randomly assigned to one of four experimental groups, consisting of 25 listeners each, in a controlled behavioral-intervention trial. There were two types of HPDs (formable and premolded) and two training formats (individual and small group). A short multimedia program, including a practice session, was presented to all 100 listeners. Results showed training to have a significant effect, for both HPDs on real-ear attenuation and attitude, but, importantly, there was no difference between small-group and individual training.