It has been widely studied that students’ academic achievement may be affected by the socioeconomic characteristics of their peers. Nevertheless, little is known on whether the relative position that students occupied within their primary school peers in terms of socioeconomic background could be affecting their academic progression from primary to secondary education. We make use of census and longitudinal data to analyse this issue for the lowest performer and largest Spanish region, i.e., Andalusia, by the use of a value-added methodology. Our results show that students’ relative socioeconomic position within their primary school peers may affect their academic progression, even after controlling by students’ socioeconomic status. This result highlights the relevance that not only students’ own socioeconomic background has on their future academic progression and, by extension, labour market position, but also the influence that their peers have on it.