This volume contains 30 papers and posters selected from the 37 presented at the 30th West Coast Conference on Formal Linguistics, including the plenary by Christopher Potts. The conference took place from April 13-15, 2012 at the University of California, Santa Cruz. The complete table of contents is available at http://www.lingref.com/cpp/wccfl/30/index.html along with abstracts and the complete papers in PDF format. This volume has been published by Cascadilla Proceedings Project, an imprint of Cascadilla Press. Proceedings from Cascadilla Proceedings Project are published in library binding, with free web access to all of the papers in the proceedings through our web site at www.lingref.com.