Participatory design (known before as ‘Cooperative Design’) is an approach to design attempting to actively involve all stakeholders (e.g. employees, partners, customers, citizens, end users) in the design process in order to help ensure the product designed meets their needs and is usable (Wikipedia, 2012).
Here is also a link to a collaborative academic paper on participatory design Design Tools and Three Steps in Participatory Design Processes: A Proposal for Better Communications among Residents and Experts, based on a Case Project of Neighborhood Park in Seoul, Korea.
The paper is from the Proceedings of the 6th Conference of the Pacific Rim Community Design Network, Quanzhou, Fujian, China, June 18-21, 2007