It has been proved that lead dithizone and carbazone complexes act as adequate initiators for radical polymerization of methylmethacrylate and also as reliable indicators for the free-radical mechanism. Lead dithizone complex, in particular, exhibited the phenomenon of color change during the polymerization process, suggesting the use of this complex as a free-radical indicator and also as a coloring material for acrylic polymers in situ. The color change observed during the polymerization process was attributed to the change in the structure of complex compounds according to a tautomerization mechanism. The presence of lead dithizone and carbazone complexes as initiators exhibited reduced molecular mass compared to those prepared in their absence, indicating their role as regulating agents during the polymerization process. The polydispersity and tacticity parameters were measured through the present work using GPC and H-1-NMR techniques, respectively. The amorphous nature of polymer chains in both the absence and the presence of the lead dithizone and carbazone was studied using X-ray diffraction, where an increased crystallinity was observed.