According to the International Classification of Headache Disorders (ICHD-2), migraine is a common disabling primary headache disorder manifesting in attacks lasting 4 to 72 hours. Migraine headaches range from moderate to very severe and are sometimes debilitating. Migraine affects 17% of women and 6% of men. The ICHD-2 divides migraine into migraine with aura and migraine without aura. The most common type of migraine, migraine without aura, is defined as a headache that occurs at least five times per month with headaches lasting between 4 and 72 hours (untreated or unsuccessfully treated), and having a minimum number of migraine attributes two of (a) unilateral location, (b) pulsating quality, (c) moderate or severe pain intensity, (d) aggravated by or causing avoidance of physical activity and one of (a) nausea and/or vomiting, (b) phonophobia or photophobia] and cannot be attributed to another condition. When migraine without aura occurs on 15 or more days per month for at least 3 months and eight of the headaches meet migraine without aura criteria, without medication overuse, the complication of chronic migraine should be diagnosed. This Future Research Needs (FRN) project is a follow up to the Comparative Effectiveness Review (CER), "Preventive Pharmacologic Treatments for Migraine." The review was motivated by uncertainty around the effectiveness, comparative effectiveness, and safety of pharmacologic treatments for the prevention of episodic or chronic migraine in adults. To identify research needs, this FRN project used a deliberative process to identify evidence gaps, translate gaps into researchable questions, and solicit stakeholder opinion on the importance of research questions. Addressing these research needs should provide information potentially of value to decisionmakers. The research questions addressed in the CER relied upon an analytic framework from the original CER. The framework describes a process experienced by adults with episodic or chronic migraine seeking preventative pharmacologic treatments. Differentiating between chronic or episodic migraine according to their clinical definitions depends on headache frequency, frequency of migraine type headaches, the presence of aura, and the possibility of headaches associated with overusing acute pain medication. However, in practice, these categories are often simplified in studies with episodic indicating fewer than 15 headache days per month and chronic indicating 15 or more headache days per month). The review addressed important KQs (KQs) about the efficacy and comparative effectiveness of these treatments (KQ 1); evaluating the safety of these treatments (KQ 2); and the identification of patient characteristics that predict the effectiveness and safety of pharmacologic treatments for preventing migraine attacks in adults (KQ 3). We used a deliberative process to identify evidence gaps, translate gaps into researchable questions, and solicit stakeholder opinion on the importance of research questions. This report proposes specific research needs along with research design considerations that may help advance research in this field.