In this work we have studied the field emission from three different types of carbon films: (i) a-C:H:N deposited using an inductively coupled rf PECVD process, where the N content in the films can be as high as 30 at%. (ii) Cathodic arc deposited tetrahedral amorphous carbon (ta-C) with embedded regions of carbon nanotube and onion structures. (iii) Unoriented carbon nanotube films on a porous substrate. These films were formed by filtering a solution of nanotubes dispersed in alcohol through the pores (0.2 um dia.) and drying.