HS&P, formerly known as Hicklin Slade & Partners, will run a national campaign aimed at gay men, targeting them with a direct response effort through press, online display and outdoor channels.
The aim is to drive traffic to the and promote the third edition of its core publications, 'Living with HIV'.
After this activity, the agency will work on reaching other demographics, with the black African community in the UK as the next brief.
The charity, founded in 1987, has relied on the clinical community, in the past, to raise awareness of its publications.
Mark Runacus, chief strategy officer at HS&P, said: "There used to be a general view that having HIV was a lonely death sentence.
"Organisations such as Nam are making great strides to change these perceptions and support those living with HIV and Aids.
"This was a fascinating challenge for us and we look forward to taking the message to those communities where there is education to be done, and where the maximum results will be achieved."
Other HS&P clients include Norwich Union, Honda, Diageo and Camelot.