Serial and parallel OT differ in the way they account for phonological generalizations referring to more than one level of the prosodic hierarchy. Vowel shortening in Latin is analyzed by McCarthy, Pater & Pruitt (2016) as a case in point. Vowel shortening takes place to optimize foot structure. In parallel OT, footing and shortening can be evaluated in parallel, but in serial OT footing and shortening necessarily take place in a serial derivation. In this paper, both the serial and the parallel analysis of Latin vowel shortening are critically discussed. After that, two other potential cases of cross-level interactions in Latin are addressed: vowel deletion and vowel gliding. For each of these cases, it is argued that a serial analysis has...