This thesis studies different aspects of the interaction between education and labor market outcomes using a still largely unexplored phenomenon: the selling of thousands of high school and undergraduate diplomas in Brazil. The first chapter describes this new database, comprising thousands of Adult High School (AHS, or EJA in Brazil) diplomas sold for individuals that never really completed their degrees. Our analysis of the performance of these individuals in the labor market shows consistent wage gains of buying a diploma, with earnings 5 percent to 8 percent higher in comparison with individuals without a high school diploma during our period of analysis. Back-of-the envelope calculations considering the pecuniary cost of buying a diploma indicate a rate of return over 100 percent, or present value corresponding to two to six months of wages. We interpret this as potential evidence of alternative mechanisms: (i) signaling effects in a context of labor markets with incomplete information, (ii) asymmetric employer learning or (iii) learning-by-doing. The second chapter explores the same database to investigate human capital accumulation in real AHS. Initial investigation shows that individuals that completed AHS regularly enjoy a wage premium. However, compared to workers that merely bought diplomas, those who studied show no apparent advantage. Taken together, the results from the first two chapters indicate that the benefits from AHS are related to a pure diploma effect, and not to human capital accumulation. The third and last chapter explores a new database of fake college graduates between 2011 and 2016 who were exposed and had their degrees canceled following a large police investigation. We present preliminary evidence about wage gains and establish additional research questions that can be addressed with this database. As a whole, the thesis reinforces the importance of diplomas as signaling devices for the labor market.