This paper will discuss the main conceptual and methodological challenges associated with testing the impact of transitional justice (TJ) on democratic institution-building (DIB). It will begin by discussing the definition of the dependent and the independent variables, including the list of dimensions and indicators best suited to measure each of them. It will then explore the measurement challenges associated with the selection of indicators, the measurement level, and the validity of the measures. The paper will then present an overview of existing databases in the field, exploring how they have dealt with the above mentioned issues and how they can serve as sources for future research. Finally, the paper will discuss the best qualitative data collection techniques and data analysis methods for testing the impact of TJ on DIB. The paper is part of a larger research project coordinated by A. Mihr (Utrecht University) and C. Sriram (SOAS London) that will study the impact of TJ on DIB in eight countries: Brazil, Burundi, Chile, East Germany, Hungary, Japan, Sierra Leone and South Korea.