This paper is an overview of research on the L2 vocabulary acquisition, attrition and relearning of LDS missionaries. The first section summarizes studies which used a common research design to examine both the learning and the loss of L2 vocabulary in three East Asian and three Indo-European languages by the English-speaking missionary population. In the second section, using a framework of the savings paradigm from cognitive psychology, an overview is given of our initial vocabulary relearning study (Hansen, McKinney & Umeda, 2000) , followed by findings from recent analyses of longitudinal data collected from a subset of the same returned missionaries a decade later (Hansen, Kim & Taura, 2010).