Objective: Worldwide, little information is available about the extent to which children with mental disorders in the general population receive treatment from health professionals that meets minimal clinical practice guidelines. This study identifies the percentage of 6–17 year olds with mental disorders in the 2013–2014 Australian national survey of mental health who had sufficient contact with health professionals during the 18 months after the survey to have received treatment meeting criteria for minimally adequate treatment (MAT). It also identifies factors associated with children having this level of contact with health professionals. Method: Mental disorders were identified using the Diagnostic Interview Schedule for Children Version IV completed by parents. Health professional attendances and psychotropic medications dispensed were identified from linked national Medicare Benefits Schedule and Pharmaceutical Benefits Scheme records. Results: Only 11.6% (95% confidence interval [CI] [9.1, 14.8]) of children with disorders (n = 517) had sufficient contact to achieve study criteria for MAT. Furthermore, among children with mental disorders who had severe functional impairment and whose parents perceived that their child needed help (n = 146), 20.2% (95% CI [14.3, 27.9]) had contact sufficient for MAT, 46.0% (95% CI [37.8, 54.4]) had contact that did not achieve MAT criteria and 33.8% (95% CI [26.1, 42.3]) had no contact with health professionals. In multivariable regression, children with moderate or severe functional impairment were more likely to have had sufficient contact to meet MAT criteria. Conclusion: During the 18 months after being identified with a mental disorder, only a small percentage of children have enough contact with health professionals to allow provision of MAT. This may be contributing to the unchanging high prevalence of childhood mental disorders.