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Lakes provide a wide range of ecosystem services. We compile information on ecosystem services, focusing on those that are a result of lake ecological functioning. The key species, habitats, and processes underpinning important lake ecosystem services are discussed. The current status and trends in these services are assessed by examining recent data on lake ecological indicators. These allow inferences to be made on the current state and trends of lake ecosystem services, while also pointing to the main anthropogenic pressures that threaten these services. Many ecological processes contribute to the assimilation and sequestration of nutrients and contaminants, thereby improving water quality and habitats. However, assimilation and purification processes are vulnerable to excessive nutrient loading rates and to invasive species and the deterioration of these processes is often rapid and difficult to reverse in lakes. We provide evidence that these processes have deteriorated in many lakes due to land-use intensification in sensitive lake catchments and to the proliferation of non-indigenous invasive species. We also discuss valuations of lake ecosystem services, which show that lakes provide substantial economic benefits to various regions of New Zealand. Finally, we present a case study illustrating the complex interactions between multiple anthropogenic pressures and lake ecosystem services.