This paper reported on the effects of input enhancement and consciousness-
raising on the acquisition of English prepositions following some verbs and adjectives. The participants were Thai college students divided into three groups: one control group (CG) and two experimental groups (E1 and E2). The instruments were a pre- test and a post-test. Three mini-lessons were given within eight days. Three post-tests were administered within about eight weeks after the last lesson. One finding showed that, compared to the pre-test, all groups scored significantly higher in all post-tests. However, compared to the immediate post-test, the scores from the two delayed post- tests declined significantly, but the scores from the two delayed post-tests of each group were not significantly different from each other. The scores from each post-test of the three groups did not reveal any significant difference.