This paper analyzes firms' location when workers endogenously choose to qualify for professional skills but when they remain uncertain about the potential match between their personal abilities and/or affinities and the firms' specific production tasks. By qualifying in a region where firms agglomerate, workers benefit from higher prospects of good match. At the equilibrium, we show that firms may locate in a single cluster, symmetric clusters or even asymmetric clusters. Comparative statics with respect to product market demand and labor supply parameters are provided. © 2003 Elsevier Inc. All rights reserved.