In the following dissertation, I develop heuristics for collaboratively and sustainably contributing to community infrastructures through writing. Based on the findings of an observational study on how students enrolled in my first year composition and service-learning class created new media writing projects with community partners and were able to contribute to local infrastructures, I argue that students mobilized and invented different kinds of knowledge depending on what technologies, modes, and genres they had experience with and access to as part of the class. In order to do this, they formed a strong network of skills, ideas, and other resources with their community partners. Reflections on these findings, along with my experiences doing community media work in Lansing, Michigan, enable me to develop a rhetorical understanding of infrastructures as networks of activity and resources--like knowledge about modes and genres--that support writing. From this perspective, I ultimately argue that the most effective means of building and sustaining infrastructures is for writers to leverage their networks to create new types of resources that can then be used to do rhetorical work in the world. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]