Recently published research has shown that both an atmospheric oxidation process and an oxygen-independent process can contribute to the accelerated deterioration of paper and that both types of processes are accelerated by acidity. In the present study, the relative importance of these two processes has been determined experimentally as a function of pH of buffered samples of rag and newsprint papers. Both the loss of strength and the yellowing of the papers were monitored. The results indicate that over the pH range generally encountered in papers (pH 4 to 9), the relative importance of these two types of processes is not altered significantly.