If your goal is to have an immersion vacation and you need to learn some language skills to get that going, here are some options for Spanish language schools.
Hispaniola Academy (Calle Arzobispo Nouel 103, tel. 809/688-9192 or 809/689-8350, www.hispaniola.org ) is in the Ciudad Colonial  and offers a variety of packages. A week-long intensive course is the quickest. There are also accommodation options with a family or in a hotel. The academy also has Dominican culture classes like cooking and dance.
Instituto Intercultural del Caribe (Aristides Fiallo Cabral 456, tel. 809/571-3185, www.edase.com ) offers packages ranging in intensity, length, and accommodation choices. This school operates on the intercultural exchange philosophy; there are opportunities to mix and mingle with language students from the Dominican Republic , and instructors often take the learning outside of the classroom to apply it in the real world.