This dissertation focuses on the general research topic: organizational structure, agency costs, and monitoring in financial institutions. The first topic is on the organizational structure change in the insurance industry. Using data of demutualized insurers in the property-liability insurance industry from 1997 to 2009, this paper examines whether the benefits following demutualization are consistent with the motivations suggested by the literature. First, the findings support the access to capital motivation; however, the requirement of capital differs between demutualized insurers with and without surplus notes. Demutualized insurers with surplus notes show the long-term need of capital to maintain high growth; those without surplus notes indicate the weak need of capital. Second, this paper finds that organizational flexibility post demutualization facilitates demutualized stock insurers to involve in merger and acquisition activities which provide an important channel to raise capital and to pursue growth and diversification. Third, this paper finds evidence that demutualized insurers increase premiums written in commercial lines, lower underwriting expenses, but take more investment risks post demutualization. The second topic is on the benefits and costs of using bank loans. Using a unique sample of firms that make their initial public straight bond offerings from 1987 to 2015, this paper finds support for both the monitoring effect and the hold-up problem of using bank loans. This paper finds a significant decrease on the at-issue yield spread of initial public bond offerings for firms with higher strength of bank monitoring. On the other hand, this paper finds that banks hold-up low credit quality firms but not high credit quality firms before they enter the public bond market. After issuing initial public bonds, low credit quality firms experience a significant decrease of loan spread; this is not found in high credit quality firms.