In this thesis speech data from a Greek SLI child (age 4.3) are examined with respect to the morphosyntactic properties of the verbal domain. The morphosyntactic categories under study are Tense, Aspect and Subject-Verb Agreement. The central observation about the child's verbal grammar is that tense marking appears to be the most problematic domain, whereas errors of S-V agreement are rare. Tense marking in obligatory contexts appears to be correctly used for present tense (90% correct use) but problematic for past tenses (56.8% correct use). Imperfective aspect predominates in verb forms, since Present tense is the most frequently used verb form. Verb forms marked for imperfective aspect underspecified for tense features (Past tense forms) substitute Perfective Past and Perfective modal forms in contexts that require verb forms marked for perfective aspect. S-V agreement is correctly marked in all persons singular and plural (over 98% correct marking).