This paper is organised as follows. §1 examines the phonological and phonetic aspects of syllable structure, vowel deletion, CL and stress in Piro, and identifies the problems to be solved. After specifying the theoretical assumptions in §2, I present a proposal to account for Piro's prosodic structure, segment deletion and CL (§3). §4 compares the proposal with several conceivable alternatives, and touches on issues regarding prosodic licensing and stray erasure. A brief conclusion is given in §5. Syllabic and morale structures in Piro 405 (2) a. CV te.no 'tall' ki.ni.ma 'bead bracelet' b. CCV slo.ta 'clam' tla.hwa 'toad' c. CCCV nkno.ya.te 'my turtle' ra.su.ka.mtna 'they ran' The distribution of three-consonant clusters is limited, however: they result only from morphological concatenations that involve monoconsonantal affixes (Lin 1987, 1997a): (3) a. n-knoyate->nkno.ya.te'my turtle' my-turtle b. hasuka + m + ta + kaka-»ha.su.ka.mtka.ka 'cause to run' (79) to flee-TRANSITORY-THEME CLOSURE-CAUSATIVE As noted in Lin (1987, 1993), one important aspect of Piro syllable structure is that no sonority constraints are placed on the combinations of consonants. The examples in (4) show that any two consonants can occur in either order. Word-initial geminate clusters are also allowed, as shown in (4g). All permissible consonant clusters occur in both word-initial and word-medial positions. (4) a. b. c. d. e. f. g. tpa mwenutu wyoptota ksu tmennu smota nnika curve 'cheap' 'we receive' 'tube' 'flaw' 'blunt point' 'I eat' pto wmahatya ywalitxa skota mtenotu msa wwuhene ... s group 'we lack' 'hip' ' lower abdomen' 'short' ' empty corn cob' 'our child' The only exceptions to such considerable freedom of consonant clustering are certain combinations of obstruents that are similar in place and/or manner of articulation : 4 (5) a.