Students bring different skills and knowledge to the language classroom, but one of the most important resources they possess --- their own first language --- is often underused or even ignored. The use of the mother tongue in the foreign language classroom has often been officially discouraged. In the past it was felt that students were not learning the target language if they were speaking their own. But the process of observing the target language and learning how it works can be dramatically enhanced if students' mother tongue is used in the right way.