Xtraordinary People has appointed the agency to help raise awareness of the charity, remove the stigma of dyslexia and promote understanding of the condition in schools.
Account director Anna Gibson will lead the work, which will initially focus on the launch of a new government-backed initiative next month.
The Outside Organisation is also looking after the charity's celebrity support. Gibson said it had already signed up Richard Branson and Jamie Oliver, both of whom are dyslexic, to ‘show dyslexia doesn't prevent you from achieving amazing things'.
Xtraordinary People founder Kate Griggs won the Sheila McKechnie Foundation Social Inclusion Award last week. It was presented to her by Chancellor Gordon Brown.