We report on the hydrolytic polymerization of zirconium in aqueous solution using the transient optical response of the fluorescent molecule 1-pyrenecarboxlyic acid (PCA) as a probe. We have measured the fluorescence lifetimes and rotational diffusion dynamics of PCA in "aged" aqueous solutions of tetravalent zirconium to understand the ability of fluorescent probes to report on the structural aspects of hydrous metal oxide self-assembly. The degree of polymerization, and therefore the extent of solute organization, is controlled by allowing the Zr4+ solutions to polymerize (age) for selected amounts of time at 85 degreesC. Fluorescence lifetimes and reorientation times measured for PCA in zirconium solutions increase rapidly, approaching a constant value after 30 h of aging. The data point to growth of polymers that achieve a maximum volume. The reorientation data place limits, on the size and shape of polymers and provide insight into the mechanism for their growth.