Background: People with autism spectrum disorder (ASD) are three to four times less largely to be with employment compared to neurotypical others. Theory based studies may provide helpful indicators for the design and implementation of employment supports for people with ASD. Objective: This critical review examined the extent of the evidence for theory in studies on employment outcomes for people with ASD and taking into account social inequality. For the evidence, 35 studies were selected for review if they were published in the period 2000--2016 and assessed for the association between work participation with ASD applying descriptive survey or quasi-experimental design. Methods: Studies were examined for use of any theory, including four predetermined theory types: social liminality, psychosocial, behavioral, and structural-infrastructural. They were also content-analyzed to determine if they cited any evidence of social inequality influences on employment outcomes with ASD. Findings: Results indicated that none of the studies explicitly applied and tested a theory on work participation with ASD. Rather, the majority of the studies were implicitly framed on predominantly behavioral type theory with minor elements of workplace psychosocial support theory-oriented interventions. Regard of structural-infrastructural type theory addressing social inequality is incidentally addressed by a few of the studies (n = 3) that examined family income status influences. Conclusion: In conclusion, extant studies on the association between employment outcomes and ASD are seriously limited in their explanatory value by a lack of theoretical grounding. They also neglect influences of antecedent social inequality in employment outcomes with ASD. Future studies should apply specific theory to questions on employment outcomes with ASD to provide usable evidence to inform employment support policy instruments and interventions for people with ASD.