Mollusks are among the most diverse and abundant animal groups, inhabiting many aquatic and terrestrial environments. They are important ecosystem engineers, helping to structure aquatic bottom environments and providing habitat, protection, and food to a wide array of other taxa. Mollusks have been historically important to humans in many ways, and are today an economically important group worldwide. As major calcareous organisms with an extensive fossil record, they can provide important information on past climate events and oceanic changes, thus, increasing our understanding of predicted future changes. This paper presents an overview of the use of mollusks in environmental and impact studies, to provide a baseline towards a wider use of this diverse group ( and the valuable collections housed in many museums) as proxies in environmental reconstruction, climate change, ocean warming, and acidification research.