Healthy U is a self-administered intervention implemented through a tablet app with interactive learning experiences, including videos, digital games, quizzes, and role-plays. Healthy U takes youth 3-4 hours to complete. The goals of Healthy U are to: 1) Increase male youth's perception of vulnerability to unplanned fatherhood, STDs and HIV; 2) Increase male youth's self-efficacy for negotiating condom use with their partners; 3) Increase male youth's self-efficacy for using condoms correctly and consistently every time they have sex; and 4) Increase male youth's engagement with goals and dreams for their future.

The counterfactual condition for the study is a business-as-usual condition. OYA does not provide much programming to youth in its facilities related to sexual health and pregnancy prevention.

There are seven modules in Healthy U: Puberty, Birth Control, Teen Pregnancy, HIV, STDs, Healthy Relationships, and Condom Negotiation. Each module has six sections: Introduction and Review, Narrative Teen Portrait, Information Film, Activity/Game, Dramatic Film, and Imagination Challenge. The Introduction and Review has videos lasting 1-2 minutes where the Healthy U "host" introduces each module. In the Narrative Teen Portrait for each module, a different teen discusses their experience with the topic for 1-3 minutes. The Information Film lasts 5-18 minutes per module and provides factual information. For each module, the Activity/Game includes multiple choice, true/false, or other games. The Dramatic Film lasts 5-17 minutes for each module and shows a fictional account of a teen experiencing the topic. Finally, the Imagination Challenge asks the youth to imagine a scenario, such as going to a health clinic to obtain free condoms.

The outcome was based on four survey items. Youth who responded "no" to the first item: "Have you ever had sexual intercourse?" were coded as "0". Youth who responded "no" to the second item: "Have you been out of a close custody OYA facility any time in the past three months?" were also coded as "0". Youth who responded "no" to the third item: "During the last 3 months, did you have sexual intercourse, even once?" were also coded as "0". Youth who responded "yes" to the first three items and provided a valid response greater than zero to the fourth item: "In the last 3 months (include only the time you were outside of a close custody OYA facility), how many TIMES did you have sexual inter-course?" were coded as the value they entered.

The outcome was created by subtracting the sexual intercourse outcome from the following measure based on four items. Youth who responded "no" to the first item: "Have you ever had sexual intercourse?" were coded as "0". Youth who responded "no" to the second item: "Have you been out of a close custody OYA facility any time in the past three months?" were also coded as "0". Youth who responded "no" to the third item: "During the last 3 months, did you have sexual intercourse, even once?" were also coded as "0". Youth who responded "yes" to the first three items and provided a valid response greater than zero to the fourth item: "In the last 3 months (include only the time you were outside of a close custody OYA facility), how many TIMES did you or your partner use a condom when you had sexual inter-course?" were coded as the value they entered. Youth who responded "none" to the fourth item were coded as "0".

The outcome was calculated as the average response based on a scale of 1 (strongly disagree) to 5 (strongly agree) for the following four items:

• Condoms should always be used if a person your age has sexual intercourse.
• Condoms are a hassle to use.
• Condoms are important to make sex safer.
• Using condoms means you don't trust your sexual partner. Youth needed to complete three of the four items to be included in the calculation.