A staffing agency proposal letter is an official document that outlines the services a staffing agency intends to provide. It outlines details including the number of people to be hired, job descriptions and qualifications, terms of employment, and timeline for completion of services. The proposal letter should also explain any additional services that the staffing agency has to offer, such as background checks or training programs. This letter should be written in a professional yet engaging tone in order to draw clients in and convince them that the agency is right for the job.