The conducting polymer polyaniline can be synthesized in high yields as nanofibers with diameters less than 100 nm and lengths of up to several micrometers. Though typically carried out in acidic media, the polymerization can also take place in aqueous solution. We have investigated the formation of these materials by removing aliquots from the solution at timed intervals and then quenching the reaction with ammonium hydroxide to produce a sequence of �snapshots� throughout the synthesis. Scanning electron microscopy reveals a morphological evolution from non-fibrous to fibrous materials. This transition can be roughly correlated to UV-Vis and FTIR spectroscopy and suggests that nanofibers are not formed until the emeraldine state of polyaniline is reached. These nanomaterials have also been synthesized in the presence of polysiloxane-stabilized gold nanoparticles. The resulting nanocomposites may offer enhanced electrical conductivity and additional reactivity relative to the well-characterized conducting polymers alone. They are being explored for use as components in biosensors and other electronic devices.