This paper explores the role of deflection rate partitioning in analyzing creep crack growth rate data for creep-ductile and creep-brittle materials. The first part of the paper assesses the fundamental basis of this approach and its application to creep-ductile materials, while the second part attempts to extend this analysis to creep-brittle materials. Numerical analyses of compact type specimens from an elastic, power-law creep material undergoing creep-ductile and creep-brittle behavior are conducted to assess the deflection rate partitioning approach. It is shown that the current criterion for qualifying the creep crack growth rate data as creep-ductile is conservative. Conditions are proposed which must be met for steady-state creep crack growth to occur in creep-brittle materials.