There are multiple contractors involved in the item development process:
Educational Testing Service (ETS) is the primary contractor responsible for the development of the items. They have between 12 and 14 full time personnel and access to other specialists on an as-needed basis.
The NAEP Education Statistics Services Institute (NESSI) is a group of individuals who provide assessment services to NCES. Within this entity, there is a team of Ph.D. level item development and Master’s specialists who work within the NAEP Division.
Pearson performs the scoring and the training of the scorers for the NAEP assessments.
Westat conducts the data collection in the field.
Fulcrum performs technology tasks related to the NAEP assessments.
Finally, a logistics contractor arranges meetings and travel for the various activities related to assessment development.