This article grounds the morality of secession on two forms of collective self-determination: one manifests the communal goods of secessionists and the other the value of shared political institutions. Secession is morally valuable when the two are incompatible such that the claimant confronts persistent alienation. For remedial rights theories, only ‘strict violations’ permit secession. For primary rights theories, ‘broad violations’ grant secession as a last resort, and so this thesis, ‘collective self-determination as nonalienation’, should be accepted regardless. First, as the (...) two collective forms of self-determination develop two forms of territorial rights, it supplements cogent accounts of territorial justification for, and claims to, secession. Second, as persistent alienation can have both strict and broad interpretations, it also provides moral grounds shared by remedial and primary rights theories if they concede the value of collective self-determination. The strict sense refers to persistent coercion that violates personal autonomy and nullifies state legitimacy. The broad interpretation denotes long-term political frustration caused by unreasonable prevention of greater collective autonomy that even legitimate states may achieve. Third, to verify whether this amounts to long-term political frustration and to address persistent alienation, secession should be regarded as a last resort, despite its support from the primary rights account. (shrink)