This study utilizes data from clinical reports of 1441 youth and adults in the USA to examine the types of problematic Internet experiences mental health professionals report as clients' primary or secondary presenting problems. Overall, clients who present in treatment with an Internet problem are more likely to have problems related to overuse of the Internet; use of adult pornography; use of child pornography; sexual exploitation perpetration; and gaming, gambling, or role-playing. Other Internet-related problems, such as isolative-avoidant use, sexual exploitation victimization, harassment perpetration, and online infidelity were equally likely to present in treatment as a primary problem or secondary to other mental health concerns. Some differences between youth and adult clients were also identified. Findings suggest some initial support for the importance of including Internet use, experiences, and behavior as part of an initial clinical assessment.