Neutron diffraction experiments on small particles of lead in the pores of Vycor glass are described. The small particles have a coherence length of (107 ± 20) Å; there is only a slight increase in the lattice parameter as compared with bulk lead, but an analysis of the intensity of the diffraction peaks reveals that there is an increase in the average amplitude of vibration of 28%. At least 80% of the lead in the glass is present in the crystalline state and contributes to the coherent diffraction.