Laser ablation (LA) is a unique tool for nanoparticle synthesis. The main advantages of this method are in its green character and in the possibility of a control over particle size. In this study, we examine nanoparticle formation by laser ablation under different experimental conditions and analyse the results based on the developed models. The dynamics of the laser plume expansion is examined revealing the role of the background pressure and laser pulse parameters. As a result, the ablated material is compressed and a part of it becomes supersaturated. The so-called "primary" nanoparticles are formed at this stage. Then, nanoparticle aggregation/fragmentation enters into play leading to the formation of the secondary particles. In addition, laser- assisted fragmentation of nanoparticles is also examined. Based on numerical modeling we shed light on the above mechanisms by using different numerical approaches, such as molecular dynamics, Monte Carlo, numerical hydrodynamics, and analytical analysis. Calculations are performed for metallic targets under different background conditions. The obtained results explain recent experimental findings and help to predict the role of the experimental parameters. The performed analysis thus indicates ways of a control over nanoparticle synthesis © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.