Citizen science is a transdisciplinary approach that responds to the current science policy agenda: in terms of supporting open science, and by using a range of science communication instruments. In particular, it opens up scientific research processes by involving citizens at different phases; this also creates a range of opportunities for science communication to happen This article explores methodological and practical characteristics of citizen science as a form of science communication by examining three case studies that took different approaches to citizens' participation in science. Through these, it becomes clear that communication in citizen science is ‘÷always’ science communication and an essential part of “doing science”.