This article analyzes one of the most common transfer-generated errors in Spanish-speaking Italian learners’ interlanguage: The presence of the differential object marking, i.e. the presence of the preposition “a” in front of an animated or specified object. Italian, in standard SVO sentence, does not mark the object differently. This transfer phenomenon is motivated by different factors, both psychological and linguistic. The high frequency in Spanish of this syntactic feature, the scarcely perceptible and thus noticeable absence of the “a” in the phonetic chain and the easiness by which such structures are transferred into a closely-related language such as Italian are some of the reasons responsible, according to the author, of this error. A section dedicated to pedagogical interventions aimed at discouraging this transfer phenomenon is presented in the second part of the paper. Input enhancement activities, corrective feedback techniques such as prompts and recast and classroom activities are suggested.