The Arrhenius equation is reviewed, and procedures required to determine activation energy are described. Activation energy values for a variety of papers are listed for several physical properties. Room temperature rates of change estimated with the Arrhenius equation are compared with other permanence test results using rank correlation coefficients. Data and references suggest that acidity is not a reliable singular factor on which to judge potential permanence of paper. Single-temperature aging tests are shown to yield misleading information on papers with different activation energies, while multitemperature studies will detect differences in temperature-dependent rate constants. Accelerated-aging ovens that control temperature, humidity, and continuous replenishment of air are described. See also AATA 15-389.