Background: A practical test that measures the information and communication technology (ICT) skills students need for effectively using ICT in primary education has yet to be developed (Oh et al., 2021). This paper reports on the development, validation, and reliability of a test measuring primary school students' ICT skills required for effectively using ICT (the ECC-ICT test). Objectives: Based on existing literature, three ICT use domains were identified for effectively using ICT--"Effective," "collaborative," and "creative use" of ICT. For these three domains, 24 corresponding teaching objectives were identified from a widely used digital literacy framework. Thirty-four test items cover these teaching objectives in an online test. Methods: A mixed-method approach was used for the ECC-ICT test. Four pilot rounds [superscript (n=25)] implemented qualitative interviews for cognitive validity and refining the test items, followed by a qualitative usability study[superscript (n=6)]. Confirmatory factor analysis and ANOVA provided quantitative insight into the large-scale test administration[superscript (n=575)]. Results and Conclusions: Composite reliability of our conceptual 3-factor confirmatory model showed that the test reliably measured primary school effective use of ICT ([omega] = 0.82), collaborative use of ICT ([omega] = 0.80) and creative use of ICT ([omega] = 0.64). Convergent validity (ranging from 0.41 to 0.46) was acceptable. Internal consistency (ranging from 0.84 to 0.91) and discriminant validity (HTMT values below 0.90) are good. ANOVA results show that mean test scores are higher for students in higher grade levels (p < 0.001). The post hoc Bonferroni results show that most grade-by-grade comparisons are significant (p < 0.001).