The purposes of this study are to test whether the processing of subject relative (SR) clauses is easier than that of object relative (OR) clauses in Turkish and to investigate whether the comprehension of SRs can be better explained by the linear distance hypothesis or structural distance hypothesis (SDH). The question is examined in two groups of second language (L2) learners of different proficiency levels and a few agrammatics expected to show a similar pattern. Each participant is asked to comprehend 15 sentences containing SRs and ORs via a picture selection task. The results indicate that comprehension of SRs is easier than that of ORs for intermediate level L2 learners, whereas there is no significant difference between the types of relative clauses for early learners. Another result is that early learners produce errors similar to those of agrammatics, which are explained through trace deletion and referential strategy. These findings on Turkish provide significant support for the SDH.