There is no logical reason why one compound preposition is right in a certain context, whereas another one is
wrong. To use compound prepositions correctly is difficult because most of them have several functions. In
addition, different prepositions have sometimes similar uses. Such prepositions cause difficulty to Iraqi EFL
university students because syllabus designers and teachers do not concentrate on such sort of prepositions. This
study aims at identifying and analyzing the errors Iraqi EFL university students encounter in using such
prepositions and finding the reasons behind students’ errors. A diagnostic test is designed and applied to a sample
of 100 Iraqi EFL university students at their third year. In the light of the students’ responses, it can be concluded
that the majority of Iraqi EFL university students fail to recognize and produce such propositions. Moreover,
they do not realize the function of such prepositions because they do not discern their meanings and most books
of grammar do not list their meanings or uses. As such, the researcher uses Hornby (2006) to clarify their
meanings. The subjects’ errors are attributed to the following factors: (i) interlingual transfer, (ii) intralingual
transfer, (iii) context of learning, and (iv) communication strategies.