The International Long-Term Ecological Research (ILTER) network offers a unique scenario to explore scientists’ perspectives on the benefits, opportunities and challenges of citizen science (CS) as these are embedded in local communities over long time periods. We describe some general trends obtained from a survey conducted among ILTER scientists, which include the following: about half of international scientists are involved in CS initiatives that primarily focus on biology and environmental science research; they train volunteers via short in-person workshops or written instructions and involve them multiple times in collecting samples and data; and they often acknowledge volunteers in peer-reviewed publications.