Despite the vast amount of literature that has dealt with the increasing presence of Anglicisms in multiple domains in Spanish, little attention has been paid to the use of Anglicisms by teenagers in internet forums, which have become a popular medium of communication among adolescents. This paper intends to analyze the use of Anglicisms by Spanish-speaking teenagers in this context. After having examined the contributions in www.forojovenes.com for six months (October 2015 to March 2016), the findings reveal that teenagers tend to use pure Anglicisms more frequently than other kinds; despite the existence of equivalents for some of the examined Anglicisms, the English term is chosen; the most prolific subject area to the use of Anglicisms is that of ICT. Sources such as corpus CREA, the project COLA and several well-known dictionaries have allowed to verify these uses. The employment of Anglicisms in this field may be justified in many cases, due to the lack of Spanish equivalent, but in other cases, these borrowings are connected with the prestige and sense of modernity associated with English.