The preparation of organic/inorganic hybrid materials composed of polymer coated magnetic colloids and their controllably assembly on the mesoscale will be discussed. Controlled radical polymerization, namely, atom transfer radical polymerization (ATRP) and nitroxide mediated polymerization (NMP) are the key synthetic tools that were used to prepare organic copolymer surfactants. These polymeric surfactants were then used to prepare polymer coated ferromagnetic colloids of metallic cobalt, which were capable of assembling into extended 1-D mesostructures. The synthesis and functionalization of these colloidal building blocks will be summarized, in particular, strategies to incorporate these materials into polymer thin films will be discussed.