This study investigates the potential effect of the management of working capital on the value of the industrial companies in Jordan, by studying determinants (company size, company growth, and leverage) that affect company value measured by Tobin's Q (TQ). Also it uses an improved methodology to produce three indexes (benchmarks) that can present the suitable information for mangers and investors. To achieve the objectives of the study, a sample constituted by forty-one (41) industrial companies was studied. The study covered the period from 2000 to 2007. Regression analysis and Mann-Whitney-U Test were used to test the hypotheses of the study. The results show that R2 for small size companies is higher than for big size companies. And it is noted that the average TQ for companies with big size is higher than the average for small-sized companies.