This study seeks to examine the existence of Instant Messaging language phenomenon among female teenagers in some Jordanian private schools and its influence on their learning experience, mainly literacy. It also raises questions about the characteristics of textese as well as teachers' attitude towards their students' use of SMS language in their academic writing. The methodology used in this study involves the descriptive and quantitative analysis of writings taken from 320 female teenagers in four different private schools in Amman, Jordan following National and International Programs as well as the responses to a questionnaire filled out by 100 EFL teachers. Upon the examination of these writings, it becomes clear that Instant Messaging language appears in students' writing, and teachers have reservations towards its use by their students in their writing. Data suggest that teachers should raise students' awareness of this issue to help them effectively control and enhance the influence of Instant Messaging on their academic writing.