ACES is an online library of multimedia activities and exercises that can be used to enhance behavioral skills training in teen sexual risk reduction interventions. The goal is to enable teachers and practitioners to improve program delivery by using these activities to supplement existing interventions, and consequently promote active youth engagement and involvement. ACES has two components: (1) The Youth Activities Library (YAL) (2) The Teacher Training Library (TTL) The activities in the Youth Activities Library are aimed at youth and include multimedia audio-visual presentations, role-play demonstrations, group discussion activities, video clips, quizzes and polls, as well as traditional classroom exercises, handouts, and homework assignments. The library also includes classroom presentation materials that provide factual information on HIV/AIDS and STD awareness (incidence, prevalence, modes of STI transmission etc.). These activities in the YAL are arranged into 40 separate modules, with each module focusing on the following themes in the area of teen HIV/AIDS/STDS and pregnancy prevention: Refusal skills and resistance to peer pressure Assessing risks/using safety skills Stress management/ conflict resolution Dating and relationship decisions Negotiation skills/contraception use HIV/AIDS/STD awareness Safe sex practices Abstinence/delaying sexual activity Sexual orientation Buying contraception Condom demonstration Parent-child communication To help teachers use these modules, ACES also includes tutorials for teacher training. The ACES Teacher Training Library (TTL) is aimed at teachers and will train teachers and practitioners by offering video demonstrations in conducting role plays, group discussions and general classroom management strategies.