The effect of short glass fibres on the polypropylene (PP) crystallization kinetics and thermodynamics has been investigated. Although at high fibre percentages in the composite the spherulitic limits are not clearly defined, the presence of crystalline entities is evident. A marked decrease of the half time of PP crystallization, tau(1/2) as well as a sensible increase of the overall crystallization rate, K-n, has been observed in the presence of fibres. However, at any crystallization temperature, a maximum of tau(1/2) is reached at 20% glass fibre content in the composite followed by a continuous decrease as fibre percentage increases. A slight increase in the Avrami exponent as temperature increases is obtained although it is relatively independent of composite composition. In all cases an instantaneous nucleation takes place, a nucleant effect of fibres is evident, and no transcrystallinity has been observed with these short glass fibres. Fibres give rise to a marked increase in the crystallinity of the samples. The chain folding energy for PP crystallization (sigma(e)) decreases with fibre content, and a minimum is observed at 20% fibre content.