Human pluripotent stem cell-based in vitro models that reflect human physiology have the potential to reduce the number of drug failures in clinical trials, and offer a cost effective approach for assessing chemical safety. Here, human embryonic stem (ES) cell-derived neural progenitor cells, endothelial cells, mesenchymal stem cells, and microglia/macrophage precursors were combined on chemically-defined poly(ethylene glycol) (PEG) hydrogels and cultured in serum-free media to model cellular interactions of the developing brain. The precursors self-assembled into 3-dimensional (3D) neural constructs with cortically organized neuronal and glial cells, interconnected vascular networks, and ramified microglia. Replicate constructs were highly reproducible by RNA sequencing (Spearman's correlation coefficients, ? = 0.97) and robustly expressed neurogenesis, vasculature development, and microglia genes. Finally, linear support vector machines were used to construct a predictive model from RNA sequencing data for 240 neural constructs treated with 60 toxic and non-toxic chemicals, which then correctly classified 9/10 blinded compounds. Overall design: Note that all cell types were derived from the H1 human embryonic stem cell line. 11 samples for initial quality control (triplicate day 13 neural progenitor cells; quadruplicate day 21 neural progenitor cells cocultured with mesenchymal stem cells and endothelial cells; quadruplicate day 21 neural progenitor cells cocultured with mesenchymal stem cells and endothelial cells and migroglia/macrophage precursor cells), quadruplicate samples of H1 ES cells as a control for comparing to untreated toxicity study samples, and 288 samples associated with toxicity screening (all samples formed using neural progenitor cells, endothelial cells, mesenchymal stem cells, and microglia/macrophage precursors).