Spanish-speaking (SS) children with language impairment (LI) present with deficits in morphology and verb argument structure. These language areas may be useful for clinical identification of affected children. This study aimed to evaluate the discrimination accuracy of spontaneous language measures with SS preschoolers to tease out what combination of grammatical measure(s) were responsible for the LI deficits, and to determine the role of verb argument structure and syntactic complexity in identifying SS children with LI. Two sets of experiments were conducted on the spontaneous language samples of SS preschoolers with and without LI using discriminant function analyses. The study found that (a) mean length of utterance in words (MLUW) and ungrammaticality index in combination are fair to good discriminators of preschoolers with LI; (b) a morphology model combining correct use of articles, verbs, and clitics fairly discriminates LI children but may miss children whose language has limited syntactic complexity; and (c) semantic-syntactic complexity measures, such as MLUW, theme argument omissions, and ditransitive verb use, should be considered in the assessment of Spanish LI. The children who were bilingual and Spanish dominant in the study were classified as accurately as the Spanish-only children.