The formation of cadmium sulfide (CdS) particles in the gaps between the layers of the multilamellar vesicles is described, introducing a new pathway in the preparation of nanometer-scale particles. The in situ structural characterization of both the CdS particles and the vesicles as a reaction medium was performed in the early and final states of the process by using anomalous small-angle X-ray scattering (ASAXS) and freeze-fracture methods. The ASAXS method provides the separation of the scattering of nanoparticles present in a small amount, whereby the monitoring of their formation and growth in the whole time range of manufacturing has become possible.