Project-based Learning and Assessment is the third book in the series of books on  Mother-Tongue Education in Hong Kong. Since mother-tongue education has expanded in Hong Kong, many schools have started exploring school-based curriculum and innovative teaching methods, among which project-based learning is a key programme. Project-based learning encourages students to `learn by doing’, which means they have to solve problems by assembling and applying knowledge from various subjects. The positive effect of learning by doing has been widely acknowledged. How should assessments be brought out according to the curriculum and teaching methods of project-based learning ? How should teachers assess students’ achievements in project-based learning? These are not easy questions to answer. We believe that encouraging students to learn how study is the true value of assessment. The Support Centre for Teachers Using Chinese as the Medium of Instruction (CMI Centre) of the University of Hong Kong co-operated with schools to explore the relationship between assessment and teaching. The book is a summary of the ideas and research gathered. We hope that the assessment methods raised in the book such as graphics, self-assessment, mutual assessment, study archives, the mutually formulated assessing standards, etc., may help teachers to conduct project-based learning more effectively.