This edited collection contains 13 selected papers presented at the Romance Turn IV conference, which was held at Université François Rabelais, Tours, France, in 2010. The volume reflects the diversity of interests of the contributors, not only in the learning contexts investigated (first language acquisition, typical or impaired, and bilingualism), but also in the linguistic properties being explored, in both syntax and phonology, and the languages under examination (work not only on Romance languages such as French, Italian, Brazilian Portuguese, European Portuguese, Romanian, and Spanish, but also comparative studies involving Basque, Modern Greek, and Cypriot Greek). Such a variety allows for multiple comparisons, which corresponds to the objective of the Romance Turn: providing an interactive platform for exchanges between researchers on the acquisition of Romance languages from a generative perspective. The volume is divided into two parts: the first part includes two papers presented as plenaries, one on L1 acquisition of morphophonology in European Portuguese (by M. João Freitas) and one on L1 acquisition of relative clauses in Italian (by Adriana Belletti), while the second part comprises 11 papers by Nikos Amvrazis, Isabel García del Real and Maria José Ezeizabarrena, Giuliana Giusti, Kleanthes Grohmann, Elaine Grolla, Virginia Hill and Mihaela Pirvulescu, Tihana Kraš, Juana Liceras, Anca Sevcenco and Larisa Avram, Katérina Palasis, and Francesca Volpato.