This chapter presents a comparative analysis of four Participatory Multi-Criteria Approaches (PMCAs) usually applied in sustainability assessments (SMCE, MCM, 3-SPM and INTEGRAAL). Such approaches are presented in detail and subsequently compared to each other according to three elementary yet crucial questions: who assesses?; what is assessed?; and how is it assessed? Results outline potential synergies and theoretical incompatibilities between the four approaches. The analysis also supports future PMCA applications when choosing one particular approach according to: key meta-principles (i.e., epistemological stance, methodological emphasis); logistical constraints (e.g., time, budget); local idiosyncrasies (e.g., pertinent geographical scales, power asymmetries); and organisational factors.