The knowledge relating to the effect of learning a second language (L2) on the mother tongue (L1) is relatively limited. Most studies focused on linguistic and reading skills, but we did not find studies relating to handwriting performance. Our study focused on the transfer effect of handwriting performance from Hebrew L2 to Arabic L1. The sample consisted of 123 native Arabic speaking fourth-grade students, of whom 64 attended monolingual schools, and 59 attended bilingual (Arabic-Hebrew) schools. We evaluated students' Arabic handwriting speed and legibility as well as their handwriting automaticity, reading performance, motor control and non-verbal intelligence. Results showed that after controlling for reading speed, handwriting automaticity and motor control, the monolingual students outperformed their bilingual peers in handwriting speed but not in legibility. In addition, using hierarchical regression analysis, our results indicated that beyond the contribution of handwriting automaticity, reading speed and motor control, that explained 27% of the variance in handwriting speed, the model of education of L2 (monolingual vs. bilingual schools) had a unique contribution, and explained an additional 2% of students' handwriting speed. We discuss these results with regard to the stage of students' second language acquisition, language dominance, as well as the complexity of the Arabic versus Hebrew languages.