Nanocomposite materials containing both gold and cobalt were synthesized using block copolymers as agents for controlling spatial organization of the nanoparticles. The targeted polymers are polystyrene- block-poly(alkyne-functional)styrene copolymers where the alkyne groups were specific for incorporation of cobalt carbonyl, a precursor for cobalt nanoparticles. Cobalt-composite materials utilized diblock copolymers made by nitroxide-mediated polymerization (NMP), but extensive investigation revealed participation of the alkyne-functional groups in this polymerization method. By using polymerization solvent and low conversions, NMP could be used to make the desired diblock copolymers. A post-polymerization modification route utilizing NMP polymers of 4-bromostyrene with Sonogashira coupling of terminal alkynes to yield the desired polymers was therefore investigated. Successful coupling was obtained with room temperature conditions for terminal alkynes, 1-hexyne and phenylacetylene, on homopolymers with low molecular weight. Phenylacetylene was also successfully coupled on homopolymers of high molecular weight (up to 70 kg/mol) and multiblock copolymers. Finally, this class of diblock copolymers was extended by inclusion of a thiol endgroup, from synthesis by reversible addition-fragmentation chain transfer polymerization (RAFT), allowing attachment to gold nanoparticles (AuNPs) and thereby creating the possibility for inclusion of multiple metals in these systems. Gold nanoparticles were synthesized in situ from hydrogen tetrachloroaurate using thiol endgroups on the RAFT diblock copolymers and superhydride as reducing agent. Ex situ syntheses using blends of diblock copolymers with pre-made gold nanoparticles were also investigated. After incorporation of cobalt carbonyl into the gold-composite materials by formation of cobalt carbonyl adducts with pendant alkyne groups in one block of the polymer, carbon monoxide ligands were removed by solvothermolysis or thermolysis in thin films to yield cobalt nanoparticles or elemental cobalt species. Gold-cobalt nanoparticles formed by solvothermolysis showed magnetic response despite residual carbon monoxide ligands. Gold-cobalt nanocomposites formed by thermolysis in film had organization from the polymer, but were not magnetic.