This paper formulates a generalisation about a difference between alliteration and rhyme in verse: alliteration is subject to a locality constraint which does not hold for rhyme. Alliteration holds only within a verse constituent or between adjacent verse constituents. To demonstrate this, I describe the major verse traditions which involve systematic alliteration. This discussion is placed in the context of a more general account of a distinction between inherent form (exemplified by linguistic form, and possibly some kinds of metrical form) and communicated form (a self-description licensed by evidence provided by the text). Though it is subject to a locality constraint (reminiscent in some ways of a linguistic constraint), alliteration is nevertheless an instance of communicated form.