Without proper motor assessment, children with autism spectrum disorder may be placed in educational settings that are inappropriate for their motor abilities. However, many practitioners find it challenging to choose which assessment to use to assess these children, especially with the number of instruments available. The purpose of this study was to present findings from a case study that compared and contrasted four widely used developmental instruments (i.e., Bruininks-Oseretsky Test of Motor Proficiency-2, BOT-2; Movement Assessment Battery for Children-2, MABC-2; Peabody Developmental Motor Scales-2, PDMS-2; and Test of Gross Motor Development-Second Edition, TGMD-2) that were designed for motor skill assessment for children. A 5-year-old boy with autism participated in the study and completed all four motor skill assessments. The child completed all gross motor skills included on the four assessments, within the gymnasium of the local elementary school, and fine motor skills were assessed in a quiet room. Results revealed that the child performed better on the PDMS-2 and the BOT-2 out of the four instruments. In conclusion, each motor assessment instrument has strengths and limitations. Practitioners and researchers should consider their assessment goal when selecting a testing instrument. If the goal is to increase time engaged in on-task behavior, a quantitative approach such as the MABC-2 and the BOT-2 may be best. If the goal is to describe qualitative changes, the TGMD-2 may be best. If the goal is to assess qualitative and quantitative performance, the PDMS-2 may be best.