Cardiovascular malformations (CVMs) are the most common birth defect, occurring in 1% to 5% of all live births. Genetic, epigenetic, and environmental factors all influence the development of CVMs, and an improved understanding of the causation of CVMs is a prerequisite for prevention. Cardiac development is a complex, multistep process of morphogenesis that is under genetic regulation. Although the genetic contribution to CVMs is well recognized, the genetic causes of human CVMs are still identified infrequently. This article discusses the key genetic concepts characterizing human CVMs, their developmental basis, and the critical developmental and genetic concepts underlying their pathogenesis.