Afghan Persian has a rhythm rule that shifts a strong stress to the left when it occurs near another strong stress. Metrical theory (see LLBA 12/1, 7800555) states this shift as a change in the configuration of hierarchical values where the relationships stronger than & weaker than apply not only to adjacent syllables, but also to groups of syllables, words, & phrases. This rule accounts for the differences in stress patterns on words in isolation & in some phrases. By assuming the rhythm rule & a rule of stress assignment, it is possible to account for both word & phrasal stress for Ns, adjs, & prepositions. These two rules are sufficient to correctly assign relative stress to words of up to four syllables & to phrases. Alternatively, it takes six fairly complex rules written within the framework of the Standard Theory to account for the same data. Most interesting, however, is the fact that the metrical rules correctly predict the stress differences between similar phrases with different underlying structures. Within Standard Theory these stress patterns must be treated as exceptional, & can only be accounted for by a number of otherwise unmotivated rules