[Corrected version of paper originally published in: L. Conathan et al., eds. (2000), Proceedings of BLS 26, 247-257.  Corrections limited to formatting and font errors.]
 

Certain phonological phenomena, such as the lengthening of vowels in stressed syllables or the attraction of stress to heavy syllables, are best accounted for by means of markedness constraints that make specific reference to strong positions (M/str constraints). However, not just any markedness constraint can be relativized to strong positions, or incorrect typological predictions about phonological neutralization would be made. This paper develops a theory of M/str constraints that correctly allows for those that are empirically attested, while ruling out typologically problematic constraints. The basis of the proposal is the Prominence Condition, a restriction that holds of the universal constraint inventory such that the only legitimate M/str constraints are those that enhance perceptual prominence.