Comorbidity between problem gambling and mental health concerns such as anxiety and depression is common. Further, the treatment needs of people with co-occurring gambling and mental health concerns may be different from those of problem gamblers who do not have a co-occurring mental health concern. The present study is a two-arm, double blinded, parallel group randomized controlled trial (RCT) that will evaluate whether there is a benefit to providing access to mental health Internet interventions (G+MH intervention) in addition to an Internet intervention for problem gambling (G-only intervention) in participants with gambling problems who do or do not have co-occurring mental health concerns.