Argues that understanding the psychological drivers behind SMS uptake among key user groups could open the door to a range of user-centred applications capable of transforming handset usability--and hence operator revenues--for this inexpensive form of text messaging. Combines the findings of our own web-based survey of SMS users with psychological evidence and research on related text-based conversational systems to draw out lessons for a user-based approach to the design of mobile phone handset displays that capitalise on the social affordances of SMS texting.