Background: Parents often recognize problems in their child's development earlier than health professionals do and there is new emphasis on the importance of involving parents in the diagnostic process. In Gothenburg, Sweden, over 100 children were identified as having an autism spectrum disorder (ASD) in 2009-11 through a general population language and autism screening of 2.5 year olds at the city's child healthcare centres. Aims: To increase understanding of parents' lived experience of the neuropsychiatric diagnostic process, i.e. the period from the initial screening at age 2.5 years to the 2-year follow-up of the ASD diagnosis. Methods & Procedures: A qualitative design, a phenomenological hermeneutic method, was used. Interviews were conducted with parents of 11 children who were diagnosed with ASD 2 years prior. The parents were interviewed about their experiences of the neuropsychiatric diagnostic process, i.e. the time before the screening, the time during the neuropsychiatric multidisciplinary evaluation and the time after diagnosis. The interviews lasted for 45-130 min, and an interview guide with set questions was used. Most of the interviews were conducted at the parents' homes. Outcomes & Results: The essence that emerged from the data was negotiating knowledge, and the three themes capturing the parents' experiences of going through the process of having their child diagnosed with ASD were seeking knowledge, trusting and challenging experts, and empowered but alone. Conclusions & Implications: The parents expected intervention to start directly after diagnosis but felt they had to fight to obtain the resources their child needed. After the process, they described that they felt empowered but still alone, i.e. although they received useful and important information about their child, they were left to manage the situation by themselves. As for clinical implications, the study points to the necessity of developing routines to support the parents during and after the diagnostic process. Recommended measures include developing a checklist outlining relevant contacts and agencies, establishing a coordinator responsible for each child, dividing the summary meeting at the clinic into two parts, making more than one visit to the preschool, and providing a parental training programme.