Hybrid nanocomposites of cadmium sulfide $\left(\mathrm{CdS}\right)$ quantum dots and poly(propyleneimine) dendrimer having a 1,4-diaminobutane core have been produced by colloidal synthesis in degassed methanol at room temperature using third-, fourth-, and fifth-generation (G5.0) dendrimers, and their spectroscopic properties have been investigated. The nanoparticles fluoresced from 375 to $650\mathrm{nm}$ under near-ultraviolet excitation, and their absorption spectra exhibited a strong blueshift of the band edge compared to that of the bulk $\mathrm{CdS}$ . The stability of nanocomposites depended significantly, while the size and spectroscopic properties exhibited a weaker dependence, on the dendrimer generation. Most compact and stable nanoparticles were obtained with G5.0 dendrimers. Average diameter was estimated to be $2.2\pm 0.3\mathrm{nm}$ , assuming nanoparticles of spherical shape within an infinite well potential. The room-temperature luminescence has a fast component with $165\pm 5\mathrm{ps}$ lifetime and a slow component with a $40\pm 2\mathrm{ns}$ lifetime. The luminescence is partially polarized with an initial anisotropy of $0.39\pm 0.02$ .