The successful agency will be briefed to produce direct marketing campaigns aimed at attracting new donors and ensuring the continued support of existing ones.
Scope previously worked with Archibald Ingall Stretton, but parted company with the direct marketing agency 12 months ago owing to shifts in its marketing budget.
The agency had produced award-winning campaigns, including its "Read between the lines" work that scooped gold for best use of copy at the DMA Awards in 2005.
The campaign featured a job-rejection letter that used standard employment jargon alongside real reasons for rejection that were based entirely on the employer's prejudices against the applicant's disability.
Archibald Ingall Stretton scooped the business from Target Direct in 2004.
The hunt for a direct marketing shop follows the hiring in 2006 of Engage Group to overhaul the charity's Disability Now website.