The paper shows that children acquiring Yemeni Ibbi Arabic4 (henceforth referred to as YIA) go through a stage equivalent to the Root Infinitive (RI) stage found in non-null subject languages in spite of the fact that YIA is a null subject and does not have an infinitive construction. Spontaneous speech of two YIA children (2;1-2;11) showed presence of verbal inflections in 85-90% contexts. However, in a few cases, imperative forms occur in place of tensed forms, and indicate modal irrealis interpretation. We argue that the imperative form is therefore a Root Infinitive Analogue (RIA). The paper also provides evidence for a universal tendency to use non-finite forms in early stages of language development.