This study examined the effects of handwriting and spelling(grapheme-phoneme correspondence and grapheme-phoneme non-correspondence) on word-writing and sentence-writing in early childhood. Data was collected from 290 children from 5 year-olds to 7 year-olds by using Assessment of Basic Academic Skills: Writing(ABAS:W) developed by Chung(2016). For data analysis, Predictive Analytics Soft Ware (PASW) statistics 18 was utilized, by which Pearson product-moment correlation coefficients were calculated and multiple regression analysises were administered. The findings are as follows. Scores of all the sub-domains of writing were significantly different according to the age of children as the scores of an older group were found to be greater than that of a younger group. Among the sub-domains, grapheme-phoneme non-correspondence scores showed the most significant differences in scores between the groups. Also, all of the sub-domains showed positive correlations with one another, among which grapheme-phoneme non-correspondence showed the most significant correlations with the rest of the sub-domains. Handwriting and spelling were found to be significant predictors of word and sentence writing. Specifically, grapheme-phoneme non-correspondence was revealed to have a greater impact on word and sentence writing when compared to that of grapheme-phoneme correspondence. The results of this study suggest the importance of spelling instruction, in particular grapheme-phoneme non-correspondence, in writing development in early childhood along with integrated strategies to range over different sub-domains of writing development.