This is a mentored Research Career Development Award to support the career development of clinical investigators in patient-oriented research. Poor emotion regulation in autism often leads to "meltdowns" and worsening of social functioning. This research will use functional magnetic resonance imaging (fMRI) to identify specific components of emotion regulation that are problematic in autism and the underlying brain mechanisms related to these difficulties. Within the infrastructure of the Pittsburgh NIH Autism Center of Excellence, the research will include 120 12 to 18 year old children, with and without high-functioning autism/Asperger's. Participants will view fear-inducing and neutral film clips while in the fMRI scanner. Multiple methods will be used to capture emotional reactivity; most notably, participants will continuously rate their emotional status throughout their time in the scanner. The study aims to: characterize the role of perseveration in emotional responses to negative stimuli in autism; investigate the functioning of the amygdala and pre-frontal cortex and their interactions during emotional responses; and gather preliminary data on the impact of age and comorbid mood, anxiety, and inattention symptoms on individual differences in emotional responding in autism. This information can then be used to develop novel treatments to improve emotional and social functioning in autism.