New World blackbirds (Icteridae) have long served as model systems for studies of avian ecology, evolution, and behavior. However, this work has been conducted in the absence of a strong phylogenetic hypothesis for the group. We sequenced 890 base pairs (bp) of the mitochondrial cytochrome-b gene for 28 of the 29 icterid genera and subgenera recognized by Blake (1968). We found strong evidence of five lineages of blackbirds: grackles and allies; caciques and oropendolas; orioles; meadowlarks and allies; and a monotypic cup-nesting cacique lineage. However, we found little support for any further structure among these five lineages and no strong evidence supporting icterid monophyly. Our results set the stage for forthcoming work on relationships within lineages and for higher-level studies that address blackbird monophyly and relationships among lineages.