In this paper, a method to estimate crystallization kinetics considering simultaneous nucleation, growth, breakage, and agglomeration is discussed. The crystallization process is modeled mathematically using the population balance equation (PBE). The fixed pivot technique of discretization is used for solving PBE, and the gPROMS parameter estimation tool is used to estimate various kinetic parameters. Instead of estimating all the kinetic parameters in one step, the present method focuses on estimating kinetic parameters in three successive steps. In the first step, primary nucleation and growth parameters can be estimated by using simple induction time experiments. In the second step, secondary nucleation parameters can be found out by the gPROMS parameter estimation tool by optimizing the supersaturation profile. In the third and final step, the breakage and agglomeration parameters can be found by the gPROMS parameter estimation tool by optimizing the crystal size distribution. The developed method was applied to estimate the crystallization kinetics of the potassium sulfate-water system.