Elizabeth Bishop observed the central tensions in mid-century American poetics from a distance, which allowed her the space to resolve them in her own work in idiosyncratic and shifting ways. This chapter thus looks to her correspondence as an archive of an ad hoc poetic theory. There we see Bishop developing unique constellations of, first, the formality of accentual-syllabic verse and the flexibility of free verse and, second, a residual commitment to modernist impersonality and an emerging aesthetics of confessional disclosure. The chapter draws primarily on letters between Bishop and both Robert Lowell and Anne Sexton to advance its argument and offers readings of Bishop’s poems “Song for the Rainy Season” and “Poem” as evidence of their author’s unique engagement with mid-century poetics.