A Lagrangian approach is presented for the prediction of 3D dispersion in turbulent flows. A brief description of the main characteristics of the code PALAS (PArticle LAgrangian Simulation) is given and the different methods for the simulation of either a fluid particle trajectory or a discrete particle trajectory are outlined. Comparisons with experimental results for particle 3D dispersion in grid turbulence with a nonhomogeneous force field are presented and proved to be very satisfactory in most instances.