Section 300(b)(1) authorizes dependency jurisdiction without a finding that the parent’s inability to protect an incorrigible child is due to parental unfitness or neglect. At the age of 14, the minor began running away and being truant. She falsely reported that her mother had abused her. She gave birth to her first child at 15 and another a few years later. Mother tried unsuccessfully to supervise the minor, and sought help from The Department and law enforcement. The Department filed a section 300(b) petition alleging that the minor was at risk of harm due to mother’s inability to supervise or protect her. The juvenile court sustained the petition and removed the minor. Mother appealed, and the appellate court affirmed. The California Supreme Court granted review to resolve a split of authority on the issue of whether Welfare and Institutions Code section 300(b)(1) requires a finding that a parent was neglectful or in some way to blame for the “failure or inability” to adequately supervise or protect his or her child. The Court agreed with the appellate court in this case, holding that such a finding is not required. The first clause of section 300(b)(1) authorizes dependency jurisdiction without a finding that a parent is at fault or blameworthy for a failure or inability to supervise or protect. It disapproved In re Precious D. (2010) 189 Cal.App.4th 1251 to the extent that it was inconsistent. Whether it was the minor’s misbehavior or mother’s inability to supervise her does not matter. The basis for jurisdiction under section 300(b)(1) is whether the child is at substantial risk of serious physical harm, or illness, and that finding is supported by the record in this case. The Court also rejected the argument that because the minor’s incorrigibility was not shown to be the result of parental fault or neglect, the minor belonged under section 601. That argument presumes that there can be no overlap between jurisdiction imposed under section 300 and section 601. The Court specifically placed no judgment on mother’s inability to control the minor’s incorrigible behavior. When a minor’s obstinacy and defiance place her at substantial risk of serious physical harm, and a parent is unable to protect or supervise that child, the juvenile court’s assertion of jurisdiction is authorized under section 300(b)(1).