This article examines whether detail and its verifiability serve as indicators of strategy effectiveness and provide sources of credibility in voluntary qualitative disclosure. In an archival study, utilizing a difference-in-difference research design, we find that firms that introduce customer retention strategy disclosures with verifiable detail are more effective at retaining customers than are firms that introduce disclosures with nonverifiable detail. In contrast, we find no significant difference between the performance of firms that initiate disclosures with verifiable detail and that of firms that initiate disclosures with no detail. In an experimental study, we find that customer retention strategy disclosures that include either verifiable or nonverifiable detail are perceived to be more credible than disclosures that provide no detail. In combination, we infer it is the verifiability of detail that predicts strategy effectiveness consistent with the disclosure, despite detail invoking perceived credibility in such disclosure.