Four experiments are reported evaluating the effectiveness of a mnemonic procedure, called the keyword method, for learning a foreign language vocabulary. The method divides the study of a vocabulary item into two stages. The first stage involves associating the spoken foreign word to an English word that sounds like some part of the foreign word; the second stage requires the subject to form a mental image or picture of the keyword "interacting" with the English translation. Thus, the keyword can be described as a chain of two links connecting a foreign word to its English translation. The foreign word is linked to a keyword by a similarity in sound (acoustic link), and the keyword is linked to the English translation by a mental image (imagery link). The experiments compare the keyword method for learning a Spanish vocabulary with various control procedures. In all cases, the keyword method proved to be highly effective, yielding in one experiment a final test score of 88 percent correct for the keyword group compared to 28 percent for the control group. Several theoretical issues related to the keyword method are examined; practical aspects of incorporating the method into a foreign language curriculum also are discussed. (Author)