Over the years, multiple forms and doses of pharmacologic agents have been used for cervical ripening and labor induction. This chapter will review potential criteria and article situations for choosing a particular pharmacologic agent. The discussion in this chapter will be limited to comparisons between pharmacologic agents; direct comparisons between mechanical agents and pharmacologic agents will largely be reviewed in the accompanying article: Methods of cervical ripening and labor induction: mechanical. For the purposes of this discussion, the term labor induction will be limited to patients with a “favorable cervix” by Bishop’s score <6,1 whereas the term cervical ripening will be limited to patients with an unfavorable cervix and includes subsequent induction or augmentation of labor. Although the pharmacologic agent used for the initial cervical ripening process is the focus of this discussion, subsequent treatment with oxytocin may or may not be required for delivery.