Nuveen Select Maturities Municipal Fund is a closed-ended investment company. The Fund seeks to provide current income exempt from regular federal income tax, consistent with the preservation of capital by investing in an investment-grade quality portfolio of municipal obligations with intermediate characteristics. It invests at least 80% of its managed assets in municipal securities rated investment grade (Baa/BBB or better by S&P, Moody's, or Fitch) at the time of investment, or, if they are unrated, are judged by the manager to be of comparable quality. It may invest up to 20% of its managed assets in municipal securities rated below investment quality or judged by the manager to be of comparable quality, of which up to 10% of its managed assets may be rated below B-/B3 or of comparable quality. Nuveen Fund Advisors, LLC, formerly known as Nuveen Fund Advisors, Inc, is the Fund's Adviser.