We tested a social-identity relative deprivation (SIRD) model predicting Scottish nationalist beliefs and intention to vote for the separatist Scottish Nationalist Party (SNP). Data were from a survey of a large and representative sample of Scottish teenagers administered in the late 1980s. The SIRD model distinguishes effects of group-based and personal relative deprivation, which should be independent of one another. Importantly, social change beliefs should mediate the effects of both collective relative deprivation and group identification on protest intentions (in this case intention to vote for the SNP). Egoistic relative deprivation should be the strongest predictor of feelings of depression. Using structural equation modelling, the results strongly support this model and replicate in two different cohorts.