The paper investigates the capital structures of North-American REITs in different market phases. First, the paper aims at finding out how different REITs alter their capital structures in different environments. Second, it will be investigated which capital structures outperform others in different environments, such as market phases and economic circumstances. The panel data offers a spatial dimension considering cross-sectional REITs that exist in North America. The variables of the cross-sectional REITS are observed from 2003 to 2008, thus adding a temporal dimension to the analysis of six years. Through panel data it is possible to enhance the quantity and quality of the data. As focus variables the leverage, the short-term to long-term and the variable- to fixed-rate debt portions are implemented into the panel regression model. As control variables a large data set of governance variables, balance sheet and profit and loss data, as well as macroeconomic data are added to the data pool. Interaction variables will be necessary in order to show influences of variables on other variables. The effect of the capital structures on the performance of the company is to be measured. As performance measures, inter alia return on assets, return on equity, price to net asset value and stock-market performance are used.