This document discusses concepts related to disease screening and HIV testing models. It provides an overview of screening criteria and benefits and potential adverse effects. Voluntary counseling and testing (VCT) is described as an active case finding strategy and entry point to HIV care. Key aspects of VCT include pre-test counseling to assess risk and provide information, post-test counseling that depends on results, and the overall goal of helping clients gain knowledge and adopt protective behaviors. Special populations for VCT and various service delivery settings are also reviewed.