Adequate gross motor skills are an essential aspect of a child’s healthy development. Where physical education (PE) is part of the primary school curriculum, a strong curriculum-based emphasis on evaluation and support of motor skill development in PE is apparent. Monitoring motor development is then a task for the PE teacher. To fulfill this task, teachers need adequate tools. The 4-Skills Scan is a quick and easily manage- able gross motor skill instrument; however, its validity has never been assessed. Therefore, the purpose of this study was to assess the construct and concurrent validity of both 4-Skills Scans (version 2007 and version 2015). A total of 212 primary school children (6-12 years old) was requested to participate in both versions of the 4-Skills Scan. For assessing construct validity, children covered an obstacle course with video recordings for observation by an expert panel. For concurrent validity, a comparison was made with the M-ABC-2, by calculating Pearson correlations. Multivariable linear regression analyses were performed to determine the contribution of each subscale to the construct of gross motor skills, according to the M-ABC-2 and the expert panel. Correlations between the 4-Skills Scans and expert valuations were moderate, with coefficients of .47 (version 2007) and .46 (version 2015). Correlations between the 4-Skills Scans and the M-ABC-2 (gross) were moderate (.56) for version 2007 and high (.64) for version 2015. It is concluded that both versions of the 4-Skills Scans are satis- factory valid instruments for assessing gross motor skills during PE lessons.