The following principles are fundamental in the treatment provided: Systematic reinforcement (defined as a stimulus occurring as a consequence for a response, which increases the likelihood of reoccurrence of that response). Systematic reinforcement includes: implementation of schedules of reinforcement; conjugate reinforcement, application of differential reinforcement and establishing social stimuli such as praise and social attention as conditioned reinforcers. Stimulus control (defined as a stimulus that is reliably correlated with reinforcement given a certain response, or in less technical terms, a stimulus which ‘‘signals’’ that reinforcement is available given a certain response). Stimulus control is acquired through discrimination training, prompting and prompt fading and procedures for remediating stimulus overselectivity. Motivational operations (defined as operations giving stimuli reinforcing properties). For example, when teaching a child conversational skills, topics the child is highly interested in are selected; when teaching independent puzzle completion, puzzles depicting characters of interest to the child are chosen. Generalisation (acquisition of skills not specifically taught, use of acquired skills in novel situations, novel settings or across novel people, and maintaining learned skills). Generalisation is achieved through, for example, working in different settings, using varied stimuli and presenters, thinning reinforcement schedules and utilising naturally occurring reinforcers.