Computer-mediated communication (CMC) users writing in Arabic often represent Arabic in 'ASCII-ized' form, using the Latin alphabet rather than the Arabic alphabet normally used in other contexts (Warschauer, El Said, & Zohry, 2002). Analyzing ASCII-ized Arabic (AA) can give insights into ways in which CMC is shaped by linguistic, technological and social factors. This paper presents a study of AA as used among female university students in the United Arab Emirates, drawing on data from a small corpus of instant messenger (IM) conversations, and from an e-mail survey of users' experience with this form of writing. The AA in the conversations was found to show influences from computer character sets, from different varieties of spoken Arabic, from Arabic script, from English orthography and from other latinized forms of Arabic used in contexts which pre-date CMC. Users have developed creative (but variable) solutions to the constraints involved, but the purposes of AA use also extend for social reasons to situations where technical constraints do not apply.