The zero-field-cooled (ZFC) state of Co x (SiO 2) 1− x granular films was investigated with small-angle neutron scattering (SANS), low-field AC magnetic susceptibility, and magnetoresistance measurements. Films with metallic volume fraction x=0.41, which consists of 30–40 Å non-percolated particles that are superparamagnetic at room temperature, show an ordered magnetic state below 150 K consisting of 550 Å correlated regions that are aligned antiferromagnetically. The results of AC magnetic susceptibility at frequencies ranging from 0.1 to 1000 Hz agree quite well with the SANS results giving the same temperature for the onset of correlated behavior despite the different time scales of the experiments. The results suggest a magnetic transition driven by dipolar interactions among the nanoparticles. Films with x=0.32 exhibit evidence of magnetic interactions but no extended magnetic correlation. The measured magnetic correlation length corresponds to the particle size.