Aims: To develop an internet-based support and coaching model for young people with autism spectrum disorder (ASD) and/or attention-deficit/hyperactivity disorder (ADHD), and to validate the model. Method: A user centred design was applied to develop a model for internet-based support and coaching, where individuals received eight-week support via internet (chat). The model was validated by ten individuals, 15 to 26 years of age, with ASD and/or ADHD. Self-report questionnaires (Sense of Coherence (SOC), the Rosenberg Self Esteem Scale, the Manchester Short Assessment of Quality of Life (MANSA), Montgomery Åsberg Depression Rating Scale (MADRS), and the Hospital Anxiety and Depression Scale (HAD)) were distributed before and after intervention. A structured interview regarding the quality of the model, the Patient perspective of Care and Rehabilitation process (POCR), was used after the intervention. Results: The validation showed significant improvement of SOC, self-esteem and subjective Quality of Life at follow-up and the majority perceived high fulfilment/importance on the POCR. Conclusions: The model can be an important complement to other interventions for young people with ASD and/or ADHD.