An analytical phase transformation model has been used to study the kinetics of crystallization of amorphous alloys subjected to either isothermal or isochronal anneals. The model has been applied to Mg_82.3Cu_17.7 and Pd₄₀Cu₃₀P₂₀Ni₁₀, employing isothermal and isochronal differential scanning calorimetry. Applying different combinations of nucleation and growth mechanisms to the same experiments, the nucleation and growth modes dominating the crystallization and the values for the corresponding kinetic parameters, including the constant activation energies for nucleation and growth, have been determined. Further, the influence of isothermal pre-annealing on subsequent isochronal crystallization kinetics, involving a gradual change of nucleation mode up to site saturation with increase of pre-annealing, can be analyzed.