- The Green Book is the Official Directory of the City of New York, published annually by the Department of Citywide Administrative Services (DCAS). It lists contact and descriptive information on City, State and federal offices, courts and officials in the five boroughs.
- The Green Book is available in a paper format for $19.95 (plus tax, postage and shipping, where applicable).
- The first Green Book was published in 1918 under Mayor John Hylan, New York City's 96th Mayor.
- The directory was always referred to colloquially as "The Green Book" due to the cover's color but only officially became so in 1984.
- In 1957 and for a few subsequent years, The Green Book featured the traditional green color but with a velvet cover.
- Each of the Green Books produced under Mayor Michael R. Bloomberg have featured artwork by New York artists or those inspired by New York. Previous covers featured portraits of the Statue of Liberty by Keith Haring (2002-03 edition); Roy Lichtenstein (2003-04 edition); and Third Grade students at the City Hall Academy Day School (2004-05 edition).
- The 2005-2006 Green Book was printed with a saffron cover in tribute to The Gates, Central Park, New York City, the work by Christo and Jeanne-Claude that adorned Central Park during February 12-28, 2005.
- The 2008-2009 Green Book cover shows the Statue of Liberty holding a compact fluorescent lamp (CFL) and invites New Yorkers to "Help Make NYC Greener." The cover was designed by Toby Allan, a graphic artist in the Department of Parks and Recreation and is based on a cover of The Economist magazine.
- Over the years, the book has reflected the history of not only the City of New York, but the changing times of the United States. The fiscal crisis of the 1970s prohibited annual production of the directory for a number of years.
- In the 1994-1995 edition, the Green Book increased in size by 20% to make reading the directory easier.
- The last section of the Green Book includes a chronological history of New York City, population breakdown by boroughs, number of registered voters, and the assessed valuation of taxable real estate in New York City.