Citizen science (CS) is an international field based on widely accepted – although often contested – principles, typologies, and definitions. In comparison, national and local differences get relatively little attention. Our paper offers insights into the CS field in Denmark. We report on results from our 2020 study of CS activities in Denmark. The study included a literature review, a questionnaire distributed by email to members of known CS projects and allowing for access by means of self-enrolment (N=187), and a desk study of projects and actors with relation to the concept of citizen science. We found an increase in the number of CS-related publications from Danish universities from 2014 onwards. Nearly all publications were research publication, and very few directed towards larger audiences. We also found that the Danish CS field included all fields of scientific inquiry, including the social sciences and humanities. Most projects (65%) dealt with nature – biology and ecology – as an object of study. Nearly all projects used citizen science as a research method, and very few as a mode of public engagement or activism. Our survey respondents represented different CS stakeholders: universities, research libraries, museums, public institutions (agencies, public libraries, etc.), NGOs, companies, and private citizens. They were generally interested in and knowledgeable about citizen science. Collectively, they identified the following problems for CS in Denmark: volunteer retention and recruitment, institutional backing, public awareness, ethical approval of projects, acceptance of CS as a research method, and human resources for doing CS. In conclusion, CS is an emerging field at a critical stage. It has attracted interest yet still face challenges such as increasing and maintaining institutional support, consolidating existing organizational structures, creating incentives for researchers and citizens, information and advocacy, capacity-building, and ethical and legal attention.