Not all PE investors are satisfied customers, but not all dissatisfied investors sue or seek to arbitrate. Midway between inaction and legal action lies the investor complaint – an expression of dissatisfaction with some aspect of the investment relationship. Many prominent PE sponsors receive investor complaints, and the most troublesome complaints often relate to matters other than performance, such as the legality or propriety of the sponsor’s conduct. Proactive PE sponsors have developed an infrastructure and style for responding to complaints, viewing them as opportunities to engage investors and other constituencies. Failing to do so, however, can have marketing, reputational and regulatory implications given the relatively small pool of prospective limited partners, competition for fundraising opportunities and the SEC’s whistleblower bounty program. To help PE sponsors navigate that challenge, this first article in a two-part series analyzes what constitutes an investor complaint, how to document the resulting process and what common mistakes can arise. The second article will prescribe procedures for investigating a complaint and corresponding with aggrieved investors. For more on interacting with investors, see our two-part series “How Are Your Peers Responding to the Most Intrusive Requests From Private Fund Investors?”: Part One (Mar. 26, 2019); and Part Two (Apr. 2, 2019).