We investigated the predictive value of a new kindergarten assessment of handwriting readiness on handwriting performance in first grade as evaluated by the Systematic Screening for Handwriting Difficulties (Dutch abbreviation: SOS). The kindergarten assessment consisted of the Writing Readiness Inventory Tool In Context (WRITIC), the Beery-Buktenica Developmental Test of Visual-Motor Integration (Beery™VMI) and the Nine-Hole Peg Test (9-HPT). The WRITIC evaluates in kindergarten children (aged 5-6 years) prewriting skills, the Beery™VMI and 9-HPT evaluate visual motor integration and fine-motor coordination, all elements important for handwriting readiness. In kindergarten, 109 children (55 boys; mean age 70 months, SD 4.8 months) were tested with the WRITIC, Beery™VMI and 9-HPT and one year later in first grade (mean age 85 months, SD 4.5 months) with the SOS. A multivariable linear mixed model was used to identify variables that independently predict outcomes in first grade (SOS): baseline scores on WRITIC-TP, Beery™VMI, 9-HPT, 'sustained attention,' 'gender,' 'age' and 'intervention' in the intermediate period. The results showed that WRITIC-TP, Beery™VMI, and 9-HPT, 'sustained attention,' 'gender' and 'intervention' had all predictive value on the handwriting outcome. Thereby WRITIC-TP was the main predictor for outcome of SOS-Quality, and Beery™VMI and 9-HPT were the main predictors of SOS-Speed. This kindergarten assessment of WRITIC-TP, Beery™VMI, and 9-HPT contributes to the detection of children at risk for developing handwriting problems.