This article presents a case of superadditive ganging-up cumulativity in the metrical phonology of Bosnian/Croatian/Montenegrin/Serbian (BCMS). BCMS individually permits monomoraic feet and feet with a toneless head mora, but prohibits toneless monomoraic feet. Across BCMS dialects, several prosodic processes conspire against this doubly marked structure. Because of the superadditive character of this interaction, both Optimality Theory and, importantly, Harmonic Grammar require local constraint conjunction to capture the ban on toneless monomoraic feet in BCMS. This demonstration constitutes evidence for conjoined constraints in weighted constraint grammar. The study contributes to the typology of cumulativity effects by documenting superadditive ganging up in a categorical prosodic pattern, whereas virtually all previously reported cases of superadditivity have been observed in variable phonological patterns.
