This chapter explores the critical intersection between well intervention operations and well integrity management across the well lifecycle. Well interventions—including wireline, coiled tubing, and workover operations—are essential for restoring productivity, acquiring downhole data, maintaining wellbore components, and preparing for abandonment. However, these operations inherently compromise the established barrier envelope of the well, introducing elevated risks to its mechanical and hydraulic integrity. The chapter begins by identifying the drivers behind well interventions, from production enhancement to integrity remediation and regulatory compliance. It then introduces the temporary barrier philosophy, emphasizing the principle of maintaining at least two independent, tested barriers between the reservoir and the environment during any intervention. The various forms of temporary barriers—including mechanical plugs, fluid columns, pressure control equipment (PCE), and cement plugs—are discussed alongside their verification requirements and integration into barrier schematics. A detailed review of well control systems used during interventions is presented, highlighting the configurations and functions of wireline and slickline PCEs, coiled tubing BOPs, and workover/snubbing stacks. The importance of surface BOP systems, shear rams, lubricators, and injectors is emphasized, with attention to proper functionality, regular testing, and emergency response procedures. The chapter also addresses the potential for mechanical and chemical damage to well components during intervention activities. These include casing and tubing wear, elastomer degradation, scale deposition, and thermal or pressure-induced failures. Case studies and data illustrate how intervention tools and fluids—if poorly selected or executed—can compromise the well’s barrier system. The Swiss cheese model is applied to visualize how multiple, seemingly minor weaknesses can align to cause integrity loss. Finally, the chapter outlines the critical need for post-intervention integrity verification before returning a well to service. This includes reinstating permanent barriers, pressure testing critical components (e.g., packers, downhole safety valves), and documenting the verified integrity status. Trends in equipment failures, particularly for blowout preventers and safety valves, are examined to stress the importance of post-job testing and record keeping. Overall, this chapter emphasizes that successful well interventions require meticulous planning, the use of reliable and verified temporary barriers, strict adherence to well control procedures, damage prevention strategies, and rigorous post-intervention verification to preserve the well’s long-term integrity.