The goal of the Phased Implementation of a Public Health Programme: Cryptococcal Screening and Treatment in South Africa (CAST-NET) study is to establish a metrics and evaluation program to determine how best to implement a cryptococcal screening program by: location of testing, gaps in care, barriers, cost, and other potential challenges with respect to retention in care and survival. CAST-NET aims to determine the efficacy of the current WHO treatment guidelines and determine risk factors for failure of preemptive treatment.