Microarrays provide a unique opportunity for advancing medical product development and personalized medicine through the identification and qualification of biomarkers of efficacy and safety. To address reliability concerns raised in publications about microarrays (e.g., Marshall E, Science 2004; 306: 630 and Michiels S et al., Lancet 2005; 365: 488), the FDA launched the MicroArray Quality Control (MAQC) project in 2005 (http://edkb.fda.gov/MAQC/). The MAQC-I evaluated the technical performance of different microarray platforms in identifying differentially expressed genes (http://www.nature.com/nbt/focus/maqc/) and the MAQC-II has been progressively working toward consensus on the “best practices” of developing and validating microarray-based predictive models for clinical and preclinical applications.