A two-month covert survey of more than 60 stores across the country reveals that almost half of them sold M-rated titles to customers under 18.
The East County Youth Coalition, in conjunction with the National Institute on Media and Family as well as other self-described youth advocate organizations, carried out the survey.
The findings dovetail with another survey taken last year by the groups.
The coalition urged retailers to follow the rating system, which is devised by the ESRB, and give employees formal training on the importance of not selling M-rated games to minors.
The survey comes amid increasingly loud calls from Congress for the ESRB to operate more strictly and, in particular, reconsider its M rating for the controversial Wii and PS2 title Manhunt 2.