Over the last decade, it has become increasingly apparent that the cause of preterm birth is multifactorial, involving both genetic and environmental factors. With the development of new technologies capable of probing the genome, exciting possibilities now present themselves to gain new insight into the mechanisms leading to preterm birth. This review aims to develop research guidelines for the conduct of genetic epidemiology studies of preterm birth with the expectation that this will ultimately facilitate the comparison of data sets between study cohorts, both nationally and internationally. Specifically, the 4 areas addressed in this review includes: (1) phenotypic criteria, (2) study design, (3) considerations in the selection of control populations, and (4) candidate gene selection. This article is the product of discussions initiated by the authors at the 3rd International Workshop on Biomarkers and Preterm Birth held at the University of California, Los Angeles, Los Angeles, CA, in March 2005.