ZnO thin films were deposited using the DC pulsed magnetron sputtering technique to study how composition and structure influences their magnetic properties. Low sputtering powers and high substrate temperatures were used to increase adatom mobility during deposition, resulting in increased crystallite size and reduced residual stress in the films. Another set of ZnO films were Mn-doped using a second magnetron gun and the amount of doping was changed by controlling the RF sputtering power. For these films, the crystallite size increased with the amount of Mn. The magnetic properties of these materials were counterintuitive; not intentionally doped ZnO showed the highest magnetization and magnetization decreased with increasing Mn concentration.