This study investigates whether English in instructed settings is more successfully acquired by learners who are already bilingual in comparison to those with a monolingual background. There remains substantial controversy regarding potential advantages of bilingual speakers in their acquisition of additional languages, especially in heritage speaker contexts. We here contribute to this discussion by analysing the English C-test results of 1,718 bilingual and monolingual students of grades 7 and 9, sampled in schools across Germany. The bilingual students speak either Russian or Turkish (heritage language) and German (majority language). The monolingual control group was raised in German only. The main predictor variables are reading fluency and comprehension in German and the heritage languages. Additional predictor variables include school type, school year, socioeconomic status, cognitive ability, amongst others. Using correlation and regression analyses we test if reading fluency and comprehension impact proficiency in English and if bilingual students enjoy advantages over their monolingual German peers. The results reveal no systematic advantage of bilingual students, although we find significant correlations between reading fluency and comprehension and C-test results. School type, cognitive skills, among others, are predictors for English performance, whereas socioeconomic status returns no significant effect.