Citizen science – the active involvement of the public in generating data, knowledge, and evidence for research and innovation – is gaining momentum across Europe. Communities, researchers, and policymakers increasingly rely on participatory contributions to support environmental action, public health, climate resilience, and evidence-based decision making. Today, the Horizon Europe projects CROPS and ScienceUs highlight their first major results, demonstrating how community-driven science can expand, replicate, deepen, and professionalise to meet the ambitions of the European Commission and the five EU Missions.

Although developed through independent consortia, CROPS and ScienceUs are sister projects, launched under the same call to strengthen the citizen science ecosystem in Europe. Together, they illustrate two complementary approaches to a shared challenge: how to grow citizen science responsibly, effectively, and sustainably.

CROPS is developing a range of systematic protocols, frameworks, and tools that help citizen science projects increase their impact through multi-scaling approaches – depending on their goals. Over the past year and a half the project has:

• Built transnational communities connecting practitioners across Europe;
• Created a Citizen Science Champions podcast highlighting the stories of citizen science leaders across EU Missions;
• Mapped over 500 initiatives and assessed their scalability potential;
• Created a Massive Online Education Course (MOOC) to bring citizen science in classrooms;
• Launched citizen science futures visioning online workshops (Ocean and Water) running for the whole 2026, with the aim to assess the societal benefit of citizen science in Europe (sign up here).

ScienceUs identifies, supports, and accelerates outstanding citizen science initiatives, offering hands-on guidance, visibility, and capacity-building to projects ready to expand. During the first half of the project, ScienceUs has:

• Build a strategy to accelerate the replication of citizen science initiatives at EU level;
• Boost access to networks that facilitate new partnerships, joint initiatives, and links with relevant communities;
• Create an advanced training hub designed to strengthen capabilities and expand methodological and strategic expertise;
• Build comprehensive mentoring adapted to the specific needs of each participant;
• Explore a pathway into the wider citizen science ecosystem, clarifying each initiative’s positioning and potential contribution.

The two complementary projects provide a unified European narrative: citizen science is ready to grow, influence policy and achieve institutional and societal change; and Europe is building the infrastructure, knowledge, and support systems needed to scale it responsibly and sustainably.