Thin films of wurtzite Ga1-xMnxN have been grown by pulsed laser deposition from a range of Mn-doped-ceramic targets (x = 0.005-0.10). The effect of varying the substrate temperature, background nitrogen pressure and deposition time on the Mn concentration in the deposited films has been studied. Film thickness and surface roughness were monitored during deposition by in situ optical reflectometry. X-ray diffraction measurements showed that under optimal deposition conditions, the films were single phase and epitaxial. Room temperature ferromagnetism was observed over the whole range of Mn concentration, though it was observed that the moment per Mn ion increases as the concentration is reduced.