Clusterin (apolipoprotein J), a highly conserved amphiphatic glycoprotein and chaperone, has been implicated in a wide range of physiological and pathological processes. As a secreted protein, clusterin has been shown to act extracellularly where it is involved in lipid transportation and clearance of cellular debris. Intracellularly, clusterin may regulate signal transduction and is upregulated after cell stress. After neural injury, clusterin may be involved in nerve cell survival and postinjury neuroplasticity. In this study, we investigated the role of extracelullar clusterin on neuronal network complexity in vitro. Quantitative analysis of clustrin-treated neuronal cultures showed significantly higher network complexity. These findings suggest that in addition to previously demonstrated neuroprotective roles, clusterin may also be involved in neuronal process formation, elongation, and plasticity.