Yes, prior juvenile convictions can affect you as an adult.  Juvenile records are sealed when you reach adulthood and are not accessible to the general public. However, law enforcement and the courts do have access and they can be used to enhance an adult sentence. To count as a strike, the prosecution needs to demonstrate: You were at least 16 years of age when the offense was committed The offense is considered a serious or violent felony under PC 1192.7 or 667.5 You were deemed a fit and proper subject to be dealt with under juvenile law You were deemed a ward of the court because your offense was under section 707 of the Welfare and Institutions Code (murder, arson, rape, robbery, forced oral copulation, aggravated kidnapping, sodomy by force, assault with a firearm, aggravated mayhem and others)