This paper reports on a study of the impact of extensive reading (ER) on the language proficiency of a group of Vietnamese government officials studying English. Two questions were of interest. First, we wanted to examine if ER could be successfully implemented with adult second language learners beyond traditional student age. Secondly, we were interested in the relationship between learning gain and a set of ER variables, such as amount of ER materials read, the extent to which this material was perceived to be a useful and enjoyable activity. The results indicated that older adult second language learners could indeed benefit from a carefully planned and systematically implemented ER program. Further, a regression analysis showed that amount of ER was the only significant predictor of participants' gain scores. (This article was published in "RELC Journal," v30, n1 p39-61 Jun 1999)