This remarkable book looks at the grammars of children (first language [L1] learners) and second language (L2) learners in the most synoptic way since Pinker (Reference Pinker1984). To do so, it introduces a new grammar—Organic Grammar—that is both novel and a continuation of government-binding theory into the 21st century. One property of Organic Grammar is its emphasis on closed class (functional) elements, which drive the learning of the phrase marker. The authors note that “variation across languages is a function of which set of functional projections the grammar of a specific language contains” (p. 27). The book concentrates on both L1 and L2 learning, and, although it focuses on German, it includes a great deal of material on English and across all languages (Universal Grammar).

The book presents the idea of a master tree, which the language learner uses to try to fit the input to the grammar. “An alternative [that the authors take] to the idea of a uniform universal tree is that because specific languages vary in terms of their functional projections, only those for which there is evidence in the input grow in the first place” (p. 27).

Organic Grammar draws a direct connection between the stages that the child goes through and the resulting syntactic structure. The acquisition of the tree, for both L1 and L2, is directly bottom-up. So, for example, functional elements associated with the inflectional phrase are learned earlier than those associated with the complementizer phrase. Partial trees in acquisition correspond to subtrees in syntax.

This is a quietly brilliant work that sheds real light on a whole range of L1 and L2 data. Additionally, it has an innovative and all-covering theoretical view. It is deserving of the most complete and careful reading.