Autism spectrum conditions are generally perceived to affect males, with the majority of studies quoting the ratio of four males being diagnosed with autism for each female. The potential implications of this for women on the spectrum or seeking a diagnosis are wide-ranging, including healthcare professionals’ disbelief in autism in women leading to difficulties obtaining a diagnosis and misdiagnosis of other mental health conditions. In this study, a grounded theory methodology was applied to data from fifteen online blogs to explore the experiences of adult women on the autism spectrum of diagnosis of autism, and of mental health issues. The study yielded two grounded theory models: of diagnosis of autism and of mental health, which are linked through misdiagnosis of and comorbid mental health conditions. The findings suggest that there is a need for clinicians to be aware of the unique presentation of autism in women, and of the additional mental health issues which women with autism commonly experience. Additionally, targeted autism-specific interventions may be required, focussing on the core difficulties of autism as opposed to the resultant emotional and mental health difficulties.