The article summarizes the results of electron microscopic studies of ‘in situ’ crystallization of thin amorphous films. Data analysis is carried out based on the classification scheme of electron-beam crystallization of films, including structural-morphological and numerical characteristics. Layer polymorphous crystallization (as the analogue of Frank–van der Merwe growth mode), island polymorphous crystallization (as an analogue of the Volmer–Weber growth mode) and dendrite polymorphous crystallization (as an analogue of the Stransky–Krastanov growth mode) are identified. For each type of crystallization a dimensionless parameter of the relative length $\delta_0$ is determined. It is equal to the ratio of the characteristic length to the value, related to the size of the unit cell of the crystal. Based on the electron microscopic video registration of the process, kinetic crystallization curves are built for each type of the transformation.