The authors designed a chemical genomics screen with the aim of understanding genes and pathways that modulate neural stem/precursor cell differentiation. Multipotent mouse neural precursor cells isolated from cortices of embryonic day 12 (E12) embryos were subjected to spontaneous differentiation triggered by growth factor withdrawal. A quantitative whole-well immunofluorescence assay was set up to screen tool compound sets to identify small molecules with potent, dose-dependent, and reproducible effects on increasing neural stem cell differentiation toward neuronal lineage. Among the pro-neuronal compounds, kinase inhibitors were shown to exert pro-neuronal effect via a signaling pathway associated with the kinase. The global effect of hit compounds on modulating neuronal differentiation was confirmed by an in vivo mouse study and human neural stem cells culture. This study demonstrates that a phenotypic assay using cell type-specific antibody markers can be used for a large-scale compound screen to discover targets and pathways with impacts on differentiation of lineage-restricted precursor cells toward specific lineages.