This essay aims to define certain fundamental differences between two types of rhythmic patterning indigenous to English verse, and to suggest that full recognition of these differences can do much to clear up standard confusions in our prosodic terminology. A recent essay by W. K. Wimsatt and Monroe Beardsley went part way toward performing such a service by reinforcing a traditional distinction between non-syllable-counting “native” or “strong-stress” meter, patterned entirely on the accentual principle, and “syllable-stress” meters, patterned on the principle of an “interplay” of native accentual rhythms with syllable-counting techniques inherited originally from Romance-language prosody.1 It is my contention, however, that, valid as this distinction is, there is a more important one which is blurred by the tendency to emphasize regularization of the number of syllables in the verse line as the primary, if not the sole, factor differentiating the two chief metrical modes. I hope to show that, of the four so-called “syllable-stress” meters in English—iambic, trochaic, anapestic, and dactylic—only the iambic has developed in a direction radically different from the native accentual tradition; that the other three, as characteristically used in English poetry, are simply variants of the strong-stress mode; and that the very term “syllable-stress” is misleading because syllable-counting techniques may occur in strong-stress verse and the stress-factor alone does not account for all rhythmic discriminations in iambic verse. The distinction with which this essay is concerned—between the entire iambic tradition and all English verse written in strong-stress meter, whether syllable-counting or not—is, I believe, the most basic one in English prosody, necessary not only in performing formal scansions but also in understanding and appreciating significant contrasts between two very different ways of hearing and composing a poetic line.