Algae play important roles in wetland function and can be valuable indicators of biological integrity and ecological condition of wetlands. Sampling designs for algal assessment vary with objectives of programs and the algal characteristics that are measured. Both structural and functional attributes of algae can be measured, including diversity, biomass, chemical composition, plus productivity and other metabolic functions. Species composition of algae, particularly diatoms, is commonly used as an indicator of biological integrity of wetlands and the physical and chemical conditions in wetlands. These latter conditions can be inferred based on species environmental preferences and species composition of algae in wetlands. Sampling methods for algae on plants and sediments and floating in the water are well established, are reviewed in detail in another chapter of this book, and are used in streams and lakes as well. Laboratory methods are also well established for most algal characteristics with relatively standard protocols used in several national stream programs.