Minor found incompetent based on unusual immaturity and inability to understand legal concepts during dispositional proceedings was entitled to withdraw his earlier admission. The prosecution filed a Welfare and Institutions Code 602 petition alleging that the 14-year-old minor had committed a violation of Penal Code section 288, subdivision (a) (lewd and lascivious acts on a person under the age or 14 years). Minor admitted the petition and the case was transferred to the county of the mother’s residence for disposition, where he was found incompetent due to developmental delay and lack of maturity. Counsel brought a motion to withdraw the admission on the ground that minor was incompetent to enter an admission. Relying solely on minor’s written waivers in connection with his admission and certifications of prior counsel and the transferring court, the juvenile court found that minor had not met his burden of establishing good cause to withdraw his admission. Held: Dispositional order conditionally vacated and remanded to permit minor to withdraw plea. A factor that prevents a knowing and intelligent decision to enter into a plea can be good cause for withdrawal of a minor’s admission, if supported with clear and convincing evidence. While a lack of mental competence due to a mental disorder at one point in time is not probative of a different point in time, this case involved developmental competence, which concerns a linear process rather than competence at discrete points of time. Information from minor’s mother and psychologists showed that minor was unusually immature for his age and did not comprehend the legal concepts or proceedings involved in his case. This combination of factors meant that there was no reasonable basis to conclude that he was competent at the earlier jurisdictional hearing and could consult with his attorney.