There are 2.1 million children 0-15 years of age living with HIV worldwide; the vast majority have perinatally acquired HIV (PHIV), reside in resource limited low-and-middle income countries (LMICs), and are surviving into adolescence and young adulthood. In Uganda, where the proposed study will take place, there are over 130,000 children under 15 years living with HIV, the vast majority with PHIV, and tens of thousands more living with PHIV over 15 years. Youth with PHIV must contend with the negative effects of life-long viral infection and chronic inflammation on their neurodevelopment, medical status, mental health, and, for many, the demands of lifelong ART adherence – placing them at risk for not achieving these important milestones. Neurocognitive impairment (NCI) is chief among these negative effects. NCI in PHIV youth most commonly affects the neurocognitive domains of working memory, executive function and processing speed. NCI can affect youth’s ability to perform in and complete school, interact successfully with peers and adults, find employment, initiate and maintain long-term relationships, and function independently. NCI can also interfere with adherence to medication, which is critical in HIV, and increase poor decision-making and greater HIV transmission risk behaviors (e.g., unprotected sex). The first step in addressing NCI in PHIV youth is detecting and diagnosing it, but doing so in Thailand faces numerous challenges. Few neurocognitive tests exist for Ugandan youth with PHIV. The tests that do exist require highly trained personnel to administer and score, take several hours to administer, and many suffer from cultural biases because they were developed for and normed on youth in the US or Europe. Without accurate, clinically useful, and relatively brief NCI assessments that can be accurately administered by all levels of staff, researchers and clinicians will be severely limited in their capacity to assess youth with PHIV in Uganda, missing opportunities to study and detect NCI, as well as intervene. NeuroScreen is a brief, easy-to-use app for Android devices to assess for NCI that is designed to be administered by all levels of clinical staff. The app contains ten neurocognitive tests assessing processing speed, executive functions, working memory, verbal memory, and motor speed. It is standardized and highly automated, requires minimal training to administer, and does not require record-keeping or scoring. The proposed study will: (1) adapt NeuroScreen for Uganda and Luganda-speaking populations youth with PHIV and evaluated the adapted NeuroScreen’s usability and acceptability among Ugandan youth with PHIV and clinical staff; (2) generate preliminary estimates of the adapted tests’ validity indicators; (3) examine the adapted NeuroScreen’s usability and acceptability among PHIV Thai youth and clinical staff; and (3) explore associations between NeuroScreen performance and markers of inflammation and immune activation. T...