Inappropriate activation of transcription factors is a common event in cancer. These transcription factors contribute to a malignant phenotype by regulating genes involved in cellular proliferation, survival, differentiation, angiogenesis, and invasion. An important goal remains identifying the targets of oncogenic transcription factors that execute these changes. STAT proteins are among the best-studied of these transcription factors, and are involved in oncogenesis both in vivo and in vitro. They thus represent an ideal model for understanding how transcription factors cause cancer through coordinated changes in gene expression. Recent studies have employed microarray-based expression analysis to comprehensively identify STAT target genes. Analysis of these targets can provide insight into mechanisms of neoplastic transformation, and may shed light on new strategies for targeted therapy.