The goal of ATN 093 is to determine program-level factors associated with the effectiveness of SMILE in Caring for Youth Linkage-to-Care (LTC) program network at the 15 Adolescent Medicine Trial Units (AMTU). This will be accomplished by evaluating and categorizing the various LTC programs at the AMTUs and then examining the association between the LTC program characteristics (providers, practices, and systems) and the proportion of Human Immunodeficiency Virus (HIV)-infected youth, ages 12-24 years old, inclusive, linked to care and maintained in care. As such, this study focuses on LTC programs at the AMTUs as the unit of analysis and not the youth themselves.

Inclusion Criteria:

• Each enrolling site must have the capability to input field data that can be used to evaluate the effectiveness of the Strategic Multisite Initiative for the Identification, Linkage, and Engagement in Care of Youth with Undiagnosed HIV Infection (SMILE in CARING for YOUTH) Project

Research will be performed on 15 AMTU sites' ability to implement the CDC/NICHD linkage to care project. The "study population" is the 15 AMTU research sites. The 15 AMTUs are located in 12 U.S. cities (there are 2 sites located in New York City and 2 sites in Chicago) and 1 in San Juan, Puerto Rico.