This thesis consists of three essays which provide a detailed empirical investigation of the returns to education, gender wage gap and public-private wage differential in Bulgaria, Serbia, Russia and Tajikistan - countries that have received little attention in the literature. The studies are based on rich data sets which allow the most up-to- date analysis of the specific labour market outcomes. All three essays go a step further than the existing empirical literature since in each one the quantile regression results showed a much broader picture than the ones based on central tendency measures such as Ordinary Least Squares (OLS). The first essay looks at what had happened to the returns to human capital in Bulgaria over the period from early 1986 pre-transition to 2003. The study also contributes to the literature by estimating returns to education across the entire wage distribution, providing further evidence from Serbia, Russia and Tajikistan. Moreover, it deals with endogeneity and sample selection biases in a quantile regression framework. The second essay estimates gender wage gaps in the selected countries by applying a decomposition method that simulates marginal distributions from the quantile regression process. The study seeks to extend the popular Machado and Mata (2005) distributional approach by addressing the 'index' number problem suggested by Neumark (1988) and Oaxaca and Ransom (1994 and 1998). The gender wage gap decomposition is performed for each quantile of the earnings distribution by using the pooled wage structure as a non-discriminatory structure and giving a much richer picture of the influence of the covariate and coefficient effects. The third essay provides a comprehensive empirical study on the public-private wage differential in Bulgaria, Serbia, Russia, and Tajikistan. The study seeks to understand whether the differential in the public-private sector payment is explained by differences in workers characteristics or the difference in the returns to these characteristics. The endogenous sector choice is also considered. The study further analyses what has happened to the public sector hourly earnings differential at different points in the conditional earnings distribution and over time by adapting the Donohue-Heckman time-wise decomposition
