The production of nanoparticles with a well-defined size, narrow size distribution and particular shapes is of great importance in recent and future industrial applications and materials of commercial interest. This nanoparticle production process represents a major technological challenge due to the complexity of basic physical and chemical phenomena involved. Corresponding fundamental research, both experimentally and theoretically, is necessary and we present our current steps towards a improved understanding of the whole process. In recent experiments it has been shown that nanoparticle of different size and shape can be produced using an emulsion-based particle precipitation process [1,2]. The microemulsion droplets are volume-limited nanoreactors where due to the small-scale limitations the nanoparticle building process can be tailorized for size, distribution and even shape. The fundamental understanding of the all phenomena in such a process is the important prerequisite to analyze and later on control the particle production process according to the needs of the application and product. Recent dynamical experiments of Barium Sulfate nanoparticle precipitation in a microemulsion in our group [3] showed interesting shape and size variations under different process conditions. We believe that a fundamental step towards improved understanding of these effects lays in the understanding of the particle nucleation in such small confined volumes. Molecular modeling approaches can indeed be applied to this problem and we will focus in our presentation on important aspects which govern the dynamical evolution of particle populations in such systems. [1] D. Adityawarman, A. Voigt, P. Veit and K. Sundmacher Precipitation of BaSO4 Nanoparticles in a Non-ionic Microemulsion - Identification of Suitable Control Parameters, Chemical Engineering Science 60, p.3371-3383 (2005). [2] F. Rauscher, P. Veit, K. Sundmacher Analysis of a technical-grade w/o-microemulsion and its application for the precipitation of calcium carbonate nanoparticles, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 254, p.183 (2005). [3] Niemann B., Veit P. and Sundmacher K. Nanoparticle precipitation in reverse microemulsions: Particle formation dynamics and tailoring of particle size distributions, LANGMUIR 8, p.4320 (2008).