The current longitudinal study examined the development of morphological awareness (MA) in the writing of 59 (27 EL1, 32 ELL) participants in grade 3 and grade 5, using an experimental morphological error type scoring (METS) guide. The researcher -developed METS guide provided an in-depth analysis of inflectional and derivational morphological usage across five categories: omissions (MO), morphological spelling errors (Msp), morphological attempts (Mat), wrong word (WW) and wrong homophones (WH). Standardized literacy measures evaluated spelling, oral vocabulary and oral syntax. For all grade 3 to grade 5 participants the total morphological errors (TME) and morphological omissions (MO) decreased and the morphological attempts (Mat) increased. Increases in oral syntax and vocabulary correlated to increased writing performance and decreased total morphological errors (TME). Differences were observed in the correlation analysis across all morphological measures between language groups (EL1, ELL). Using a detailed morphological error analysis in children’s writing may provide an accurate measure of the development of morphological awareness and patterns of usage for morphological structures in the writing samples of diverse language groups. / Graduate