An earlier theory for the rate law&psgr;(t)=&bgr; ln(1+t/&tgr;)for strain, orq(t)=b−1 ln(1+t/&tgr;)for chemisorption, is extended to cover a law for creep in materials which has been of interest recently, and takes the form&psgr;(t)=(&bgr;/&ngr;)[(1+t/&tgr;)&ngr;−1]. The theory is formal in that it utilises only general concepts such as probability of success and attempt frequency.