Chapter XXV of Gramática de Referencia de español para italófonos (GREIT) proposes a novel approach to Spanish-Italian contrastive gerund periphrasis, by offering new lines of study and research on the Spanish language in this field. This Chapter XXV was written with a special focus on the latest theoretical, methodological and descriptive contributions in the field of theoretical and applied morphology. It is intended for professors and advanced students with an interest for the Spanish language, as well as any reader interested in teaching-learning Spanish and contrastive phonetics. This Chapter consists of five parts, in a progression that goes from Introducción to Características generales, Clasificación y uso, Otras anotaciones contrastivas and Itinerario bibliográfico. This chapter analyses the main problems of the Spanish gerund periphrasis; the Introduction and the final Bibliographic Itinerary allow readers to find their way through the main and latest lines of grammar research, as well as to set the foundations for critical study and research. The project – three volumes (I. sonidos, grafías y clases de palabras II. Verbo: morfología, sintaxis y semántica. III. Oración, discurso, léxico) directed by Félix San Vicente– relies on the work and coordination of numerous and renowned researches from various Italian and Spanish Universities. It is a collective work with a novel structure and with unified criteria and formulations, where each chapter is signed by one or more authors, who are responsible for it.