The aim of this study is to investigate the influence of state ownership in Saudi firms listed in the stock market. The first chapter studies the influence of state ownership on financial constraint on investment. Some scholars believe state ownership has a negative effect on the firm value. However, by using two measures of financial constraint, the investment cash flow sensitivity and the Kaplan and Zingales financial constraints index, the finding indicates that the existent of government ownership decreases financial constraint in firms. Also, the results show that the higher government ownership percentage the less financial constraint in firms. The second chapter studies the influence of specific company factors and the government ownership factor on capital structure. The finding shows that tangibility of assets and size have a positive association with leverage. Leverage is negatively correlated with growth and profitably. Finally, the results suggest that government ownership affects the level of leverage negatively.