Prosodic dissonance marks out those most difficult and most stimulating poetic works in rhythm. Poems that do dissonance, from Gerard Manley Hopkins to successive waves of avant-garde poetry over the last century, have confounded commentators and exposed certain analogical faultlines. Recourses to ‘musicality’ in poetry have long assumed that the ‘music’ of a poem must mean, in a word, euphony. Yet a musical poem, as Northrop Frye noted, would withhold rhythmic or rhymic resolve, sporting rugged, crabbed accents and lumbering polysyllables, a sequence of discords only ending with a harmony. Such analogies further do not take into account the centrality of dissonance in twentieth-century music. We therefore need new models and new ways of talking about prosodic dissonance that can take into account a fuller range of poetics. Prosody that attempts such dissonance can be found in the works of Jackson Mac Low, who greatly admired Hopkins. In a reading that follows Frye on Hopkins’s ‘inscape’ I claim that Mac Low seeks ‘outscape’, an emancipation of dissonant potential. Instress becomes outstress, a poetics of clashing exteriors; ‘pure projected detachment’, energy thrown outward and away from the poet, or starting out and finding in.