Two developments in 20th-century grammar are discussed, focusing on aspects that may be useful in training teachers of English as a Second Language (ESL). The two developments are (1) the large descriptive grammars based on usage surveys, which give a systematic and detailed presentation of facts of usage, and (2) procedures for analyzing a language that provide insights into how the language works. Discussion of the descriptive grammars is in two parts, those of the earlier part of the 20th century and those of the later part. The major works of each are examined, and information particularly useful to teachers is noted. Differences in the two groups of work are examined. Discussion of grammatical analysis looks at two schools of analysis, structural and transformational grammar. Central concepts of each that are applicable to ESL instruction are explored. An annotated bibliography of 18 related items is appended. (MSE)