In this study investigators propose to use implementation science (IS) to scale up and evaluate the TXTXT evidence-based intervention (EBI) as an effective strategy to increase ART adherence and retention in HIV care, ultimately leading to a suppression of viral load in youth and young adults with HIV (YYALH) participating in the intervention. Investigators hypothesize that participants who complete the TXTXT intervention will demonstrate a clinically meaningful increase in ART adherence, viral suppression, and sustained retention in care. Additionally, investigators hypothesize that the implementation of TXTXT will reach ≥80% of the intended participants, will be fully adopted by ≥80% of clinic partners, and will achieve ≥90% ratings of satisfaction and acceptability. Investigators will use mixed methods to complete the study aims: 1) determine the real-world efficacy of a regional scale up of an EBI - TXTXT - among poorly adherent YYALH, aged 16-35 years, on our primary outcomes: adherence and viral load suppression at 3-month post initiation of the intervention; and secondary outcome: retention in HIV care at 6- and 12-months post baseline, and 2) apply the Consolidated Framework for Implementation Research (CFIR) to describe the implementation process and identify barriers and facilitators needed to be addressed; and measure implementation outcomes of the TXTXT intervention using the RE-AIM framework (Reach, Efficacy, Adoption, Implementation, Maintenance). Investigators will conduct a cluster randomized controlled trial to evaluate the intervention effectiveness (i.e., ART adherence, viral load suppression) at 3- and 6-months post-initiation of the intervention. Twelve clinic sites with the ability to enroll up to 50 participants at each site (N=600 participants total) will be trained to administer the TXTXT intervention. Sites will be randomized to either start the intervention immediately (i.e., intervention arm) or waitlisted to start at 3 months post baseline (i.e., comparison arm). In the comparison arm, the study will compare pre-post differences in adherence at 3- and 6-months post baseline. Last, investigators will evaluate retention in HIV care, viral suppression, and sustained impact of the intervention at 6 months and 12 months post baseline for all study participants.