This dissertation studies two specific topics on information technologies in health care industry. (1) The status and change of integrated health care delivery system level IT spending and hospital level IT adoption between 1999 and 2006. (2) The potential link between hospital level IT adoptions and quality as quantified by procedural performance measure. The two chapters of this dissertation address those two topics respectively. Chapter one explores the status and recent Trend of IT spending and adoption across the health care organizations and hospitals in U.S between 1999 and 2006. The data used in this part come from the HIMSS-Dorenfest database, which surveys various aspects concerning information technology in health care organizations and hospitals in U.S. Two levels of data are analyzed: the IT spending data at the health care organization level and the IT adoption data at the hospital level. In the analysis, health care organizations and hospitals are grouped based on geographic regions, number of beds, revenue size, for-profit status and ownership status. My goal is to examine both the cross-sectional variation and the trend over time, using several key measures of IT spending and a set of IT adoption status variables. A duration (hazard) model is applied to the data to quantify the adoption and diffusion of Health Care IT. The second chapter of my dissertation examines the procedural performance of hospitals and their potential association with IT Adoption. In this part, with a data set provided by JACHO, a group of standardized performance measures are examined for hospitals across U.S between 2003 and 2007. Variations across different groups and over time are explored. Then, combining JACHO data with the HIMSS data, I analyze the potential links between IT adoption and procedural performance at the hospital level by using a subset of the procedure measures and IT applications (components). To address (at least partly) the commonly perceived issue of endogenous technology spending and adoption, I explore a particular feature of the adoption statuses in the data. The main idea is to show the following: It is the "using of IT", but not the "purchase of IT" that actually affect the performance measures. The key assumption is that after controlling for the observables, the (unobserved) confounding factors, if any, are fixed over time for each hospital. In particular, they are assumed to be fixed over the different stages of IT adoption. Our results show that Clinical Decision Support System (CDSS) and Emergency Information System have significant, but small effects on several procedures. (Abstract shortened by UMI.) [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]