Retrograde densification of pelletized calcines and glasses having an approximate (Bi,Pb)2Sr2Ca2Cu3O10starting stoichiometry and sintered at ∼850°C can be described by first‐order rate equations. Retrograde densification in the calcine precursors was largely due to the development of open pores, and was approximately proportional to the concentration of the (Bi,Pb)2Sr2CaCu3O10phase. In the glasses, retrograde densification is mainly caused by porosity accompanying the growth of a needlelike Sr─Ca─Cu─O phase, together with (Bi,Pb)2Sr2Ca2Cu3O10and (Bi,Pb)2