This study is concerned with the structure of verb phrases in English and Spanish, and with syntactic processes involving VP and Vo. A primary focus of attention is auxiliary verbs. It is argued that the structure dominating these verbs is essentially the same in English and Spanish, as is the structure dominating auxiliaries and 'main' verbs in each language. It must be concluded that the occurrence of distinct syntactic processes affecting auxiliaries and other VP constituents in the two languages does not follow from parametrization of phrase structure. It is argued that similarities...