This article describes how assessments in PE Metrics were developed following six steps: (a) determining test blueprint, (b) writing assessment tasks and scoring rubrics, (c) establishing content validity, (d) piloting assessments, (e) conducting item analysis, and (f) modifying the assessments based on analysis and expert opinion. A task force, composed of researchers, measurement and evaluation experts, teacher educators, K-12 physical education teachers, and education administrators, was formulated. The task force then determined a test blueprint for Grades K, 2, and 5 and developed corresponding assessments to assess the standards. The content validity evidence was established by a panel of experts examining the degree to which the content of the assessments matched the content of the national standards, specifically Standard 1. A total of 30 assessments (Kindergarten = 8, Grade 2 = 11, and Grade 5 = 11) were developed. They were piloted to a total of 773 students (Kindergarten = 232, Grade 2 = 268, and Grade 5 = 273). Descriptive statistics (e.g., M, SD, frequency) were computed for each assessment. More than 50% of the means were between 2.2 and 2.8 (on a 4-point scoring rubric). Assessment responses were well distributed; only 2.2% had an SD of 0, which indicates that assessments were well developed. With some editorial changes, the assessments were ready for the final calibration of PE Metrics construction. (Contains 3 figures and 7 tables.)