The throughline of the research is that ownership plus participation drives results, while ownership alone does not.
Ownership without participation does not move the needle. A 1987 study by the U.S. Government Accountability Office (GAO) found that ESOPs do not improve worker productivity or corporate profitability in the absence of worker participation. (Source: U.S. Government Accountability Office, 1987, as summarized by the National Center for Employee Ownership.)
The gains show up when ownership is paired with high participation. A 1987 Harvard Business Review study by Rosen and Quarrey found that ESOP companies with high participation grew 8% to 11% faster per year than would otherwise be predicted, companies with medium participation grew about the same as before, and companies with low participation declined. (Source: Rosen and Quarrey, Harvard Business Review, 1987, as summarized by the National Center for Employee Ownership.)
A second study splitting companies by participation level confirms the pattern. A 1994 Washington State study by Kardas, Gale and Winther found that ownership combined with participation yielded 10.9% employment growth and 6% sales growth above expectations. (Source: Kardas, Gale and Winther, 1994, Washington State study, via RMEOC.)
Why education is part of the picture. Participation is not automatic; the research community is clear it has to be built. The ESOP Association notes that training employees on their rights and responsibilities is what lets them understand what employee ownership is and is not. (Source: The ESOP Association, "Avoid the Empty Promise of Ownership.") Practitioners echo this: the mechanics of ESOPs are a frequent source of confusion, and companies that fail to educate participants rarely reap the cultural advantages. (Sources: CSG Partners; Succession Plus.)
The takeaway for an owner: across these studies, the performance gains come from ownership combined with a culture that gives employees a genuine say, not from the transfer of ownership by itself.