Randomly hyperbranched polymers containing a core region are a relatively new subclass of materials. In comparison to dendrimeric polymers, there are many similarities, including their proposed applications. Because the core-based hyperbranched polymers can be prepared in a one-pot synthesis, they are an attractive alternative to the dendrimers, which require a laborious multistep process. This research is centered around the comparison of core-based, randomly hyperbranched poly(ethyleneimine) with the dendrimeric poly(propyleneimine) to better understand their host-guest properties. Two sizes of each polymer class were examined, and studies were carried out using the solvatochromic reporter molecule phenol blue. Absorbance and fluorescence measurements (emission and anisotropy) were utilized to determine the location of the fluorophore within the polymer. Results indicate that the phenol blue does associate with both the hyperbranched poly(ethyleneimine) and the dendrmeric poly(propyleneimine), although the association is not the same for the two polymer classes. The loading capacity of both polymer classes was also determined.