The purpose of this paper is twofold: 

• First, it provides a set of actionable guidelines for professional scientists engaging in citizen science at universities, thus helping to ensure high quality research results of citizen science projects and encouraging efficient collaboration between professional scientists and the public.
• Second, based on these guidelines, this paper provides a series of policy recommendations for universities, research funding organisations and policy-making bodies to promote excellence in citizen science

The structure of this paper is the following :

• The paper begins with an introduction to the history and state-of-the-art of citizen science.
• Second, this paper highlights some recent developments in citizen science projects run by professional scientists at universities. Three important trends are distinguished.
• Third, this paper lists some important success factors common to many existing citizen science projects, and summarises these as a set of succinct guidelines for professional scientists planning citizen science projects at universities.
• Based on these guidelines and recent trends in citizen science, the paper concludes with a set of recommendations for LERU and other universities, for research funding organisations and for policy making bodies.