The crystallization behavior of thin polypropylene films with and without 4-biphenyl carboxylic acid as a nucleating agent was investigated using high-throughput methodology in conjunction with optical microscopy. The high-throughput approach involves the use of thin films cast with a gradient in thickness, placed on a hot stage possessing a temperature gradient orthogonal to the thickness gradient. This system is used to study the effect of the nucleating agent on the morphology at different temperature and film thickness combinations. The addition of the nucleating agent, upon annealing and undercooling, results in spherulite formation 10-15 degreesC higher than neat crystallization temperatures and spherulite sizes an order of magnitude smaller than those of neat polypropylene. 4-Biphenyl carboxylic acid can have a significant effect on the morphology of thin polypropylene films.