This Organized Oral Session will address the role of citizen science in building ecological knowledge from empirical and theoretical perspectives, through a diverse panel of speakers from developed and developing countries. Speakers include field researchers studying ecology with active citizen participation in the US, Canada, France, Costa Rica, and India, GIS experts developing community mapping tools online, and ecologists exploring how ecological knowledge fits into the framework of natural resource governance in societies. The speakers also represent a range of experience and innovation, including graduate students, established junior and senior ecologists, and non-academic professionals. The session features 10 talks (c.15 min each + 5 min q&a). We start with an exploration of the role and value of indigenous knowledge in studying ecology and governing natural resources, with examples from India. The next three talks address how citizen science can go beyond monitoring (as it is most often used) towards ecological education and research. The first will share experiences from the Tucson Bird Count (http://www.tucsonbirds.org/ ) in monitoring and education, followed by talks addressing the challenges / rewards of training volunteers in complex data collection protocols for highly heterogeneous urban landscapes, and how Earthwatch volunteers can contribute to urban research. We then broaden the focus to ecosystem processes, with a talk from PRBO about how citizen gathered data improve ecosystem knowledge, followed by another addressing the phenology of plant pollinator interactions in the context of global warming and collapsing bee populations. The Great Sunflower Project marks the transition towards larger regional- to-national scale projects that leverage the internet and web 2.0 technologies, as explored by two subsequent talks. We will hear about how the internet is used in building a new national bird monitoring network (Migrant Watch) in India, followed by an exploration of how interactive online databases and GIS tools can be harnessed towards participatory mapping of ecological resources by local communities. The final two talks are also international: we will hear about monitoring butterflies as a biodiversity indicator in France; and, participatory research by farmers and volunteers joining together to study coffee farming in Costa Rica.