Our international definitions of autism and ADHD (DSM and ICD), and thus our screening and diagnostic instruments, rely on research conducted with autistic males as the dominant sample.  Consequently, autistic girls and women have been missed, now referred to as ‘the lost generation.’ In this Masterclass, we draw on recent research, our decades of clinical experience, and lived experience accounts from girls and women to share our recommended screening instruments, diagnostic procedures, and resources.  We cover differential and co-occurring conditions, report preparation, explaining the diagnosis and subsequent support.  We share adaptations for the diagnostic process to ensure it is neurodiversity-affirming and strengths-focused.