Lisa is 4 years and 5 months old and Giulia 3 years and 4 months. One morning, the girls' father is taking them to nursery school. L: ... e bravissima, ha riscaldato l'auto. E' bravissima, vera? In praising the sun for having warmed up the car, Lisa has referred to it in the feminine gender, as in the German die Sonne. Her father corrects her by using the masculine gender. F: E' bravissimo. E' if sale. L: E' un maschietto, if sale? (Is the sun a little boy?) F: E'maschife. (It's masculine.) G [determined]: E' una femmina! (No, it's a girl!) F: Forse in tedesco. (Perhaps it is in German.) is left disoriented, speechless. Giulia This book is devoted to language acquisition in children who have been expos­ ed to two languages since birth. It has often been said that the study of simultaneous bilingualism is the "most fertile ground" for the formulation of general theories on language acquisition processes, and indeed, most of the studies on early bilingualism aim in this direction. But in a sense this book serves the reverse purpose. Using the results of psycholinguistic research as a basis, I have sought to understand the peculiarities of the process of language organization in the child who faces the problem of learning two languages when other children are learning only one. Thus, the recurring theme of my study is the diversity of bilingual as opposed to monolingual acquisition.

1. An Overview of Research on Bilingualism.- 1.1 The Definition of Bilingualism.- 1.2 Previous Research.- 1.3 Description of the Present Research.- 2. Word Acquisition.- 2.1 The First Stage: The Bilingual Child Has No Equivalents.- 2.2 The Second Stage: The Child Begins to Build a System of Equivalents.- 2.3 Does the Bilingual Child Have Twice as Many Words as the Monolingual Child?.- 2.4 Summary.- 3. Development of Basic Sentence Structure.- 3.1 Sentence Structure Analysis.- 3.2 Results.- 3.3 Summary.- 4. Several Aspects in the Acquisition of Morphology and Syntax.- 4.1 Verb Tenses and Conjugations.- 4.2 Past Perfect.- 4.3 Intralanguage Hypercorrection.- 4.4 "Mistakes" of Agreement.- 4.5 Diminutive and Augmentative.- 4.6 Articles.- 4.7 Participle and Infinitive.- 4.8 Pronouns and Gerunds.- 4.9 Understanding Subtle Differences.- 4.10 Superextension of Forms into Both Languages.- 4.11 Negation, the Adjective, the Possessive, and Subject-Verb Inversion.- 4.12 Word Order.- 4.13 Summary.- 5. Interferences.- 5.1 Definitions.- 5.2 Lexical Interferences.- 5.3 Morphological Interferences.- 5.4 Interferences in Word Order.- 5.5 Semantic Interferences.- 5.6 Phonological Interferences.- 5.7 Summary.- 6. A Bilingual Upbringing.- 6.1 The First Stage: The Role of the "Sole" Interlocutor.- 6.2 The Second Stage: The Child Begins to Speak the Language of the Majority.- 6.3 The Third Stage: The Maintenance of Bilingualism.- 6.4 Summary.- 7. Conclusions.- References.