This dataset contains measurements of chemical concentrations of soil samples representing 28 headwater drainage basins completely within the Adirondack Park of New York State (ADK Park), one basin partially in the ADK Park, and one watershed 2 kilometers from the ADK Park boundary. Seven of these watersheds have been sampled 2 or 3 times over periods of 12 to 22 years. Soil samples were collected from pit faces exposed by shoveling. Total mass of organic matter, carbon and nitrogen in the forest floor are also presented for 16 headwater drainage basins in the ADK Park. Forest floor mass data were determined from samples collected with soil corers. The presented data are organized by six projects: the Adirondack Soil Monitoring Study (ADK), (2) the Adirondack Sugar Maple Project (ASM), (3) the Buck Creek and Boreas long-term monitoring watersheds (Buck-Boreas), (4) the Honnedaga Watershed Liming Project (HON), (5) the northeastern Red Spruce Study (Spruce), and (6) the Western Adirondack Stream Survey (WASS). All data are included in a Microsoft Office 365 .xlsx file with a Table of Contents tab that describes all data tabs and a tab that details the field sampling designs of each project. Each tab in the .xlsx file has also been saved as an individual comma-delimited (CSV) file. The meta-data includes references to seven files that include locational data for the sites included in the data release. These data are provided in the service definition file Adirondack_New_York_Soild_Chemistry_Data_1992_2017.sd. Descriptions of soil profiles and photos of profiles and locales surrounding pits are included for some projects. First posted April 1, 2020, ver. 1.0 Revised December 7, 2020, ver. 1.1 Version 1.1: This version of the dataset is identical to version 1.0 except for revisions to the dates in the column labeled "Date_Collected" in the worksheet labeled "Soil_Chemistry_All_Projects". Version 1.0: This version contains measurements of chemical concentrations of soil samples that were originally published in April 2020. Version 1.0 data are available upon request.