An Internet survey of 765 parents examined (1) to what extent parents wanted to be informed by ratings of harmful videogames for their children (four to 18 years), (2) which content descriptors interested them, (3) which parents were most interested and (4) how parental mediation of the child's gaming related to their interest in ratings and content descriptors. The majority of parents thought it very necessary to have ratings. Warnings of realistic 'gore and gross' were considered most important, followed by warnings regarding alcohol/drugs, fantasy violence, bad language and, finally, nudity. A LISREL model showed that the ratings and most content descriptors were used as tools for restrictive and active parental mediation, in relation to parents' ideas on negative game effects. The mediation strategy of social co-play was strongly associated with the parents' own gaming and views on positive game effects.