The concept of the "left-behind" has gained significant traction in explaining electoral behavior, most notably voting for radical-right parties. Central to this thesis is that some people feel unfairly treated vis-à-vis other groups and translate their grievances into electoral choices. Despite its intuitive appeal, the left-behind literature remains fragmented, often bundling distinct causal mechanisms and justifications for grievance under a single label. This study contributes to addressing this limitation by measuring left-behindness at the individual level. Using original survey data from Germany, Poland, Portugal, Spain, and the United Kingdom, we measure distinct dimensions of perceived left-behindness, including economic, cultural, and political ones. This refined operationalization enables us to move beyond a singular focus on the radical right and instead map the specific grievance pathways leading to a broader spectrum of political outcomes: radical-right and radical-left voting, as well as outright abstention. By disaggregating the concept of left-behindness, this research provides a more nuanced understanding of the roots and consequences of political discontent in contemporary Europe.