The potential for using virtual environments (VEs) in educational contexts for people with autistic spectrum disorders (ASDs) has been recognized. However, very little is known about how people with ASDs interpret and understand VEs. This study aimed to investigate this directly with a group of 12 adolescents with ASDs, each individually matched with comparison participants. Participants were presented with VEs to assess whether they adhered to particular social conventions, such as not walking across grass and flowerbeds en route to a cafe, or not walking between two people (ostensibly involved in conversation) en route to the bar. Whilst a significant minority of the ASD group adhered to the social conventions, others displayed substantial off-task behaviour and a limited understanding of the VE. It is suggested that some individuals with an ASD, low verbal IQ and weak executive ability require the most support to complete tasks successfully in the VE.