This study describes the minority L1 English attrition of a five-year-old boy over an 11-month period. As the child of a Japanese mother and an American father, the participant developed two L1s as a child. When he was 5;8 years old, the father left the home, resulting in attrition to the participant’s minority English. The study aims to give an overall description of attrition in a participant whose language environment has not yet been covered in child attrition studies. Changes in lexical diversity are also tracked through analysis of word types, tokens and the type/token ratio (TTR). Finally, the study tests the Regression Hypothesis, which states that language last learned is first lost. For this, losses are tracked in specific vocabulary items known to be in the participant’s lexicon prior to the onset of attrition and vocabulary that was learned immediately prior. This final result shows support for the Regression Hypothesis.
