This work reports on transition metal doped ZnO nanoparticles and compares the effects doping with different transition metal ions has on the structural, optical, and magnetic properties. Zn1−xMxO (M = Cr, Mn, Fe, Co, or Ni) nanoparticles were prepared by a chemical process for x = 0.02 and 0.05 in powder form. The powders where characterized by x-ray diffraction (XRD), spectrophotometry, and magnetometry. The Zn1−xMxO samples showed a strong correlation between changes in the lattice parameters, bandgap energy, and the ferromagnetic saturation magnetization. Unit cell volume and bandgap, determined from XRD and spectrophotometry respectively, were maximized with Fe doping and decreased as the atomic number of the dopant moved away from Fe. Bandgap was generally lower at x = 0.05 than x = 0.02 for all dopants. The saturation magnetization reached a maximum of 6.38 memu/g for Zn0.95Fe0.05O.