A biomarker is a measurable characteristic or indicator of normal biologic or pathogenic processes. Biomarkers are needed to (1) identify individuals who have the highest risk of developing epilepsy after an epileptogenic insult (susceptibility/risk biomarkers), (2) improve early diagnosis, possibly even during the presymptomatic latency period following an insult (diagnostic biomarkers), (3) characterize the disease course (prognostic biomarkers), and (4) assess disease severity or response to treatment (predictive biomarkers/surrogate endpoints). Attempts to harmonize the methodologies and procedures of biomarker data collection and analysis will increase the statistical power of preclinical and clinical studies. A strategic roadmap is needed for proposing research priorities in biomarker discovery for epileptogenesis, regulatory issues, and optimization of the use of resources, similar to those devised for cancer and Alzheimer disease research. This chapter will discuss potential genetic and molecular imaging biomarkers, with examples for each, emphasizing susceptibility/risk, diagnosis, prognosis, and predictive markers. In the future, pathophysiological knowledge on epileptogenesis will need to be translated from experimental and animal studies into clinical research to provide more insights into the development and progression of symptomatic epilepsy.