On 31 July 2004 at 1130 MST we captured a Mangrove Yellow Warbler (Dendroica petechia erithachorides subspecies group), the first to be recorded in Arizona and the northernmost ever. The bird was captured in a mist net along Tonto Creek (33.75415°N, 111.22273°W), which flows into the north end of Roosevelt Lake, in Gila County about 90 km northeast of Phoenix. The bird was netted in early successional riparian habitat consisting of Goodding’s Willow (Salix gooddingii) and tamarisk (Tamarix spp.) that is established along the lake’s inflows as a result of periodic fluctuations of the lake’s level. To document this significant record, we took 15 digital photographs that clearly show diagnostic features such as a chestnut face, throat, and forecrown, thin chestnut streaks on the breast, and yellow spots on the inner webs of the rectrices (Figures 1, 2). These diagnostic photos led the Arizona Bird Committee to accept this record as the first of a Mangrove Warbler in Arizona (Rosenberg et al. 2007). Although the subspecies of the Mangrove Warbler we captured could not be ascertained, the subspecies rhizophorae breeds the closest to Arizona. It is resident in coastal mangroves north to the vicinity of Bahía Kino, Sonora, Mexico (Russell and Monson 1998), about 550 km south of Roosevelt Lake.