The foundation of school success is laid early in children's lives. Consequently, assessments of academic precursors may help to identify children in need of additional support. Such early assessments could also be interesting from an international perspective when educational systems are compared. This analysis is used to inform on the comparability of Slovenian and German versions of the English on-school-entry assessment tool "Performance Indicators in Primary School" (PIPS; Tymms and Albone 2002). PIPS was also used to predict later academic achievement in the two national samples. The German sample consisted of 468 children with a mean age of about 6;6 years at school entry (48.7% girls). In Slovenia, 328 children (49% girls) were assessed (mean age of about 6;3 years at school entry). Multi-group confirmatory factor analyses for PIPS did not support weak measurement invariance. However, results indicated that the number of factors as well as the pattern of loadings seems to be comparable. Further research is needed to examine in which respects PIPS might work as a tool for international comparisons. Structural equation modelling indicated that PIPS can be used as a predictor of academic achievement and that overall academic achievement could be predicted best by early numeracy. PIPS measures of literacy and numeracy skills were specific and significant predictors of children's later language and math achievement in grade 1.