This chapter provides an in-depth examination of verification practices critical for confirming the mechanical and hydraulic integrity of well barriers immediately after construction. It begins by establishing the regulatory and operational rationale for initial integrity testing, followed by a breakdown of industry-standard procedures including pressure tests (e.g., casing pressure tests, shoe tests, and leak-off tests), inflow tests, and negative pressure tests. Emphasis is placed on test design, interpretation of pressure-volume-time (PVT) behavior, and diagnostic criteria to identify potential barrier weaknesses. The chapter also introduces logging technologies essential for evaluating the quality of cement placement and casing-to-formation bonding. Cement evaluation logs (such as CBL, VDL, and ultrasonic imaging) are reviewed in terms of operational principles, resolution capabilities, and interpretation workflows. Case studies are presented to highlight common diagnostic scenarios, such as channeling, micro-annuli, and uncemented zones. Further, the role of temperature and noise logs in dynamic cement integrity assessment is discussed. The chapter also addresses the uncertainty and limitations of various logs, offering guidelines for data integration and risk-based decisions in well acceptance. Finally, best practices for documentation, regulatory compliance, and long-term digital recordkeeping are outlined. By combining rigorous testing protocols with advanced logging interpretation, this chapter ensures that wells are placed into service with verified and reliable barriers capable of withstanding subsequent operational loads.