The degree to which a person recognizes their mental disorder, attributes symptoms to the disorder, and recognizes that treatment may be necessary is frequently referred to as clinical insight. The current study investigates whether clinical insight at baseline moderates the effects on metacognitive capacity of 40 sessions of metacognitive reflection and insight therapy among 35 participants with psychosis. Findings showed that clinical insight did not predict drop-out from therapy. Multilevel analyses provided support for our hypotheses that insight at baseline significantly moderates metacognitive gains at both postmeasurement and follow-up. Our findings demonstrate that lacking clinical insight substantially hampers the effect of this psychosocial intervention. We posit that research efforts should shift from developing interventions, which enhance clinical insight, to interventions, which are effective in absence of clinical insight.