The energy system is in a transformation for a sustainable society. The overall targets are to meet climate goals and to reach energy independence. Wind turbines provide a main solution providing electricity from renewable energy resources with a resulting enormous global growth. A challenge is however to reduce the costs for operation and maintenance to ensure good investments. Asset management (AM) aims to handle assets in an optimal way in order to fulfill an organization’s goal while considering risk. This chapter introduces AM and maintenance as a strategic tool for AM. It also introduces the reliability-centered maintenance (RCM), and reliability-centered asset management method (RCAM), which provides systematic frameworks and tools in order to optimize the maintenance effort. The chapter provides examples from previous research studies for wind turbines including maintenance optimization, RCM analysis, and novel methods for condition monitoring using fault detection and machine learning. All examples included in the chapter are based on input data from wind turbines in operation in Europe, and all have been published as part of research studies and validation of the developed models. The selected examples are results from research performed by researchers and students within the RCAM research group initiated and led by Prof. Bertling Tjernberg.