It is repeatedly mentioned in the Hong Kong Certificate of Education (HKCE) English Language examination reports that one prevalent problem in speaking assessment is the inappropriate use of stock phrases for expressing agreement. Phrases such as 'I agree.' and 'That's a good idea.' were overly used without reference to the context. In Hong Kong, English language textbooks are the primary, if not the only, sources for the local candidates to prepare for the speaking assessment. When textbook English does not accurately reflect the authentic use of expressions for agreement, candidates will probably not be able to use them appropriately in group discussion. This book is a corpus-based study focusing on a comparison between textbook English and corpus English. It aims to find out how corpus data help improve teaching and learning of agreement for local students. It is argued that corpus evidence would be useful for textbook writers to describe and explain the appropriate use of expressions of agreement in genuine English. The analysis should be useful to textbook writers and language teachers who are interested in using corpus data to teach agreement in speaking.