Length changes were measured for low-porosity hardened portland cement pastes obtained from a Type I clinker using two different grinding aids, and from a Type II clinker using four. The water-cement ration was 0.2. Curing times for most pastes were 1 and 28 days. The pastes were exposed to a relative humidity of 42.7 percent, and for 30 days length was measured at intervals of 1 day or more. The results showed 1) that the type II pastes exhibited considerably less shrinkage than the Type I pastes after 1 day of curing, but that after 28 days differences in shrinkage were slight, 2) that the shrinkage differences due to different grinding aids were slight, 3) that pastes of clinkers ground to specific surfaces of about 6500 cm2/g showed less shrinkage than those of clinkers ground to higher surfaces, and 4) that the low-porosity pastes made from the same cement with a water-cement ratio of 0.4, and one-fourth to one-third as large as those made with a water-cement ration of 0.6. The main conclusion is that volume changes can be greatly reduced by using low-porosity cement pastes.