abstract: We considered certain projection volumes of polyhedral cones. Our main result shows that the average projection volumes of cones of a hyperplane arrangement are given by the coefficients of the associated characteristic polynomial. In the case of Coxeter arrangements, the exact volumes are given by the coefficients. These results naturally relate to those of De Concini and Procesi, Stembridge, and Denham which establish the relationship for 0-dimensional projections. Joint work with Mathias Drton and Ed Swartz.