Mariachi El Bronx first started as a diversion for members of the long-running punk band the Bronx. They put on charro outfits, replaced their electric guitars with trumpet, violin and other traditional instruments, and introduced their own take on Mexican folk music (with soulful vocals in English by Matt Caughthran, a singer previously known for his howl).

Now, about seven years later, Mariachi El Bronx is hitting maturity. Recording a third album forced members to figure out where they wanted to take a group that has opened...