MOSAiCH is a cross-sectional survey that focuses on the Swiss population’s values and attitudes toward a wide range of social issues. The thematic focus of the 2020 edition lies on "Environment IV", the current module of the International Social Survey Programme (ISSP) which is repeated for the 4th time. This international part is supplemented by selected socio-demographic questions, as well as a module composed of Switzerland specific questions and a COVID-19 supplement. The questions of this Swiss part are determined by means of a public call and either expand the ISSP module thematically or measure other dimensions that are of special interest to Switzerland.