A survey of book deterioration was carried out in Yale University Library (USA) more than 36500 volumes were examined for state of the binding the structure in general physical and chemical condition of the paper, immediate need for treatment, etc. It was found that of the items surveyed, over 37 per cent had paper too brittle to survive two double folds and over 82 per cent had pH values below 5.4. Appendix includes sampling procedures, survey instructions, and statistical analysis methods. -- ICCROM