This study aimed to identify the acquisition of some selected prepositions of time by English major undergraduates at Balqa Applied University in Jordan and to reveal any significant differences among their acquisition attributed to the academic level (1st, 2nd, 3rd and 4th year levels) and to studying "English Basic Grammar" course. A random sample consisted of 197 students chosen from two colleges at Balqa Applied University in the year 2012/2013. The instrument was developed by the researcher. Results indicated that their highest acquisition was in the preposition of time (at) and the lowest acquisition was in the preposition of time (until). Findings also revealed the mean of acquisition of the prepositions of time was lower than (0.50). Findings also indicated that there is a significant difference among respondents' acquisition of the prepositions of time attributed to year-level in three prepositions (at, to, since) in favor of the third year level students, and difference in the acquisition of (on) in favor of the fourth year level students and a significant difference in the acquisition of (after) in favor of the second year level students. The results indicated no significant differences in acquisition attributed to the university college, but there is a significant difference among respondents' acquisition attributed to studying the course "Basic English Grammar" in favor of the students who studied the course. The study was concluded with some recommendations.