The Rock En Español movement has received a good deal of attention lately, thanks largely to the swelling grass-roots support for acts such as Maná and Los Fabulosos Cadillacs, as well as the high-profile soundtrack to the low-profile film Star Maps. But listening to that diverse album and the very different new releases from those two bands makes it difficult to define the genre. Maybe the Rock En Español tag is the most appropriate one: music that can be loosely defined as rock that happens to be sung in Spanish. The popular Maná, in existence since 1986, is the first Latin rock group to reach gold status in the U.S., but Suenos Liquidos ("Liquid Dreams") does little to suggest that it was musical innovation that took it that far. There's little here that would sound out-of-place next to Huey Lewis on a "lite-rock" radio station. More compelling is Argentina's Los Fabulosos Cadillacs. With jazz, reggae and rock influences rolled together, the band produces complex, diverse music. A number of fast, loud tracks start its new Fabulosos Calavera, bringing to mind prime Fishbone—with whom the Cadillacs have performed and collaborated—but the heavily Miles Davis-influenced "Nino Diamante" reveals that there's more at work here. For the full sense of the potential of non-traditional music in Spanish, Fabulosos Calavera is a fine place to start.