Inclusion Criteria:  Subject has disabling motor simple partial seizures, complex partial seizures, and/or secondarily generalized seizures. Disabling refers to seizures that are severe enough to cause injuries, or significantly impair functional ability in domains including employment, psychosocial education and mobility. Subject has seizures that are distinct, stereotypical events that can be reliably counted, in the opinion of the investigator, by the subject or parent/caregiver. Subject had an average of three or more disabling motor simple partial seizures, complex partial seizures and/or secondarily generalized seizures over the two most recent consecutive 30-day periods, with no 30-day period with less than two seizures per subject and/or parent/caregiver report. Subject failed treatment with a minimum of two anti-seizure medications (used in appropriate doses) with adequate monitoring of compliance and the effects of treatment, as determined by the investigator. Subject has undergone diagnostic testing as part of his/her standard care that has identified no more than two epileptogenic regions. Subject is male or a female of childbearing potential using a reliable method of contraception (hormonal, barrier method, surgical or abstention). Subject is age 12 or older but will be less than age 18 (has not reached 18th birthday) at the time of implantation with the RNS System. Subject is able to maintain an electronic diary alone or with the assistance of a competent individual. Subject is able to attend clinic appointments in accordance with the study schedule. Subject and/or parent/guardian must be willing and able to provide informed consent and assent when appropriate. Subject is not currently implanted with an RNS Neurostimulator or NeuroPace Leads. In the investigator's opinion, subject is able to tolerate a neurosurgical procedure.  Exclusion Criteria:  Subject has been diagnosed with primarily generalized seizures. Subject requires procedures that are contraindicated based on current RNS System labeling. In the opinion of the investigator, the subject has a clinically significant or unstable medical condition (including alcohol and/or drug abuse) or a progressive central nervous system disease. Subject has been diagnosed with active psychosis, major depression or suicidal ideation in the preceding year. Subjects with post-ictal psychiatric symptoms need not be excluded. Subject is pregnant. Subject is participating in a therapeutic investigational drug or other device study. Subject is implanted with an electronic medical device that delivers electrical energy to the brain. Subject has been diagnosed with psychogenic or non-epileptic seizures. Subject has experienced unprovoked status epilepticus in the preceding year. Subject is taking chronic anticoagulants.  Note: For contraindications, refer to current physician labeling (manuals) for the RNS System available at the NeuroPace website (www.neuropace.com).