I had hoped not to be the first to respond to this question, since it is a very important one but difficult to answer.
I think it is useful to distinguish between what some refer to as "systems thinking" compared to the application of systems tools, such as social network analysis, systems dynamics or agent based modeling, etc. Systems thinking is inherently relational, it views occurrences and outcomes of systems as being produced by the relationships and forces that affect the system both internally and externally. For example, it views the uptake of tobacco use among adolescents as affected by the nature of the relationships an individual has with peers and family members, as well as the relationships that exist among peers and family members. It is a way of thinking about how things occur and generally views the world as dynamic and non-linear. The application of systems to real world problems frequently requires the development of systems models, such as systems dynamics models, of how a system is believed to work and the model is continuously refined and tested.
So now to the question. Usually when I am looking to understand a new area, I look for review or overview articles that help me frame the issues and concepts. There are a number of very good sources that one can recommend on systems thinking, most of which are available online or through Amazon in paperback, including:
- Donella Meadows, Thinking in Systems , 2008. This is an easy introduction to a number of systems ideas and concepts.
- Bob Williams and Richard Hummelbrunner, Systems Concepts in Action, 2009. This is also an introduction to systems concepts particularly focused on program evaluation.
- Fritjof Capra, The Web of Life, 1996, also an easy read in paperback.
- Alberto-Laszlo Barabasi, Linked: The New Science of Networks.
- Linton C. Freeman, The Development of Social Network Analysis, 2004. Provides a historical view of network approaches.
- Gerald Midgley, Systemic Intervention, 2000, a more technical but interesting characterization of stages of systems thinking.
There are several journals devoted to systems concepts and other journals, such as the American Journal of Public Health (2006) have published issues on systems approaches.
There are a number of people who have written in depth about community interventions and systems approaches, including Jean Schensul, Ed. Trickett, and others. If you wish to e-mail me at firstname.lastname@example.org, I may be able to pull together a few articles that you might find useful.