Most EFL teachers emphasize vocabulary size at the expense of vocabulary depth, thus neglecting lexical relations such as collocation, etc. Therefore, the current research intends to study the relationship between collocational competence and general language proficiency along with testing the go-togetherness of quantitative and qualitative aspects of lexical knowledge. To that end, 30 senior EFL students were selected from two Iranian universities through a tailored TOEFL test. They received an MC test of lexical (n + v) collocations. The results showed a relationship between the scores on TOEFL and the collocation test, and between the scores on the collocation test and the vocabulary section of the TOEFL. Therefore, collocational competence is much related to general proficiency and that the learners' qualitative knowledge accompanies their quantitative knowledge, implying that collocation must be attended to properly at the right time through direct teaching or consciousness-raising techniques.