This study investigates the correlations between information structure and syntactic structure with particular reference to Spanish. It examines in detail notions like "topic" and "focus", and several topicalizing and focusing mechanisms such as Clitic left-dislocation, Pronominal left-dislocation, Topicalization, Right-dislocation and Focus Preposing. It distinguishes two different "topical" elements -Sentence Topic (STopic) and Background - and suggests that in Spanish STopics occupy a preverbal specifier position while Background elements occupy dislocated positions.