This Handbook presents and critically evaluates the methodologies used to assess the impact of trade on various areas of decent work. To that end, it traces the evolution of theories and methodological approaches ranging from the macro (country), through the meso (industry/sector), to the micro (firm and worker) level. The Handbook examines the strengths and weaknesses of these approaches, taking into consideration their underlying assumptions, data requirements and the scope that they provide for analysing broader labour market outcomes, including those that can be measured using decent work indicators. Particular attention is paid to micro approaches, since analysis at that level, especially using linked employer-employee data sets, allows one to understand better the distributional effects of trade. Such data sets make it possible to take into account not only firm and worker characteristics but also their interactions, potentially leading to more realistic conclusions.