The changes in morphology and the crystallization kinetics of amorphous Cr 5Si 3 were studied by means of in situ resistivity measurements and hot stage transmission electron microscopy (TEM). The crystallization process is controlled by nucleation and growth during the continuous heating as well as in the isothermal annealing. Initially the growth is isotropic. In the later stages it becomes anisotropic due to impingement. The growth characteristics and nucleation rates were deduced from the changes in linear dimension of a growing particle with time and from the number of nucleation points as a function of time. Growth rates were found to remain constant for most of the total transformation time while nucleation rates initially increase, subsequently peak, and then rapidly decrease. The determined nucleation and growth rates were used to calculate the transformed volume fractions. The results were compared with data obtained by assuming a linear relationship between instantaneous resistivity and volume fraction and with data based on measurements of projected crystallized areas in transmission (image analysis). Kinetics studies showed that the isothermal crys-tallization follows a sigmoidal curve. The apparent activation energy was found to be ∼2.4 eV. The transformation mode parameter was found to be ∼3 which, given that the crystallization reaction is interface controlled and the nucleation may be approximated as instantaneous, suggests a three-dimensional mode of crystallization. © 1988 The Metallurgical of Society of AIME.