A novel method for the determination of particle formation rates and condensable vapor concentrations for atmospheric nucleation events is presented that is based on combining least squares optimization with aerosol dynamics. Tests of the method with simulated events show that the method is able to capture the temporal behavior of formation and growth with reasonable accuracy. Example analyses have been performed for observed particle formation bursts in Hyyti¿l¿, Finland. The results agree with previous analyses that are, in principle, based on analyzing size distribution contour plots by eye. However, the presented method also reveals detailed temporal behavior of the important processes, which is an important improvement compared to the previous methods.