Statement of work (SOW)

All three describe the work, but they hand different amounts of freedom to the contractor. A traditional SOW can prescribe methods, staffing and steps. A PWS is the performance-based form: it says what outcome is needed and how performance will be measured, and leaves the method to the contractor (FAR 37.602). A SOO is shorter still: it states the objectives, and offerors submit their own PWS with the proposal.

FAR Part 37 makes performance-based acquisition the preferred method for services, so many federal service solicitations use a PWS or a SOO, often with a quality assurance surveillance plan that explains how the government will check performance.

In the uniform contract format, the work statement lives in or is referenced by Section C, and if it is a separate document it is listed in Section J. Task order requests under an IDIQ usually attach a PWS directly.

With a SOW, the technical approach shows you will do each prescribed task well. With a PWS, it shows how your method meets each standard and how you will measure it. With a SOO, your proposed PWS is itself evaluated, so it must be clear, measurable and complete. In every case, each task belongs in the compliance matrix and in the outline.