This paper examines the ability of 256 university students to detect and correct errors related to different linguistic aspects of Catalan, by means of a test including correct and incorrect sentences. The sentences included aspects of Catalan prescriptive grammar, errors caused by interference from Spanish, and discursive aspects (adequacy, coherence and cohesion). In addition to that, the ability of the students has also been linked to data from their language use and linguistic experience in the following areas: language spoken in the family, language spoken with friends, and formal and informal languages of preference. The results show that students whose preferred language is Spanish or either Spanish or Catalan are less competent than those using Catalan on a regular basis. Taking into account the type of error, students who use preferably Spanish or both languages show significantly worse results in the error detection task (in sentences containing grammar and interference errors) than those who prefer Catalan. In contrast, no significant differences are shown regarding discourse errors when the students’ linguistic use is considered.