The effectiveness of interphase precipitation strengthening in microalloyed steels depends on the temperature dependence of the solubility of the precipitation phase in austenite and on the temperature utilized in soaking. Using an approximate method of calculating the solubility of microalloying elements in the presence of both carbon and nitrogen, a precipitation strengthening potential parameter was developed. On relating this parameter to the chemical compositions and thermal histories of microalloyed steels, it was determined that the interphase precipitation strengthening determined in this and other studies increases linearly with the strengthening potential parameter. On the basis of the linear dependence of precipitation strengthening on the precipitation potential and other observations, it appears that interphase precipitation strengthening is not due to the Orowan looping mechanism but rather to interactions of gliding dislocations with the strain fields of coherent precipitates.