| Official Name: | Nassau Lake, New York |
| Settlement Type: | Census-designated place |
| Pushpin Map: | New York#USA |
| Pushpin Label: | Nassau Lake |
| Coordinates: | 42.5367°N -73.6086°W |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | New York |
| Subdivision Type2: | County |
| Subdivision Name2: | Rensselaer |
| Subdivision Type3: | Towns |
| Subdivision Name3: | Schodack Nassau |
| Area Footnotes: | [1] |
| Area Total Sq Mi: | 1.80 |
| Area Land Sq Mi: | 1.52 |
| Area Water Sq Mi: | 0.27 |
| Area Total Km2: | 4.65 |
| Area Land Km2: | 3.94 |
| Area Water Km2: | 0.71 |
| Population As Of: | 2020 |
| Population Density Km2: | 254.77 |
| Timezone: | Eastern (EST) |
| Utc Offset: | -5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | -4 |
| Elevation Ft: | 420 |
| Postal Code Type: | ZIP Code |
| Postal Code: | 12123 (Nassau) |
| Area Code: | 518/838 |
| Blank Name: | FIPS code |
| Blank Info: | 36-49555 |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 2812769 |
| Population Total: | 1004 |
| Unit Pref: | Imperial |
| Population Density Sq Mi: | 659.66 |
Nassau Lake is a census-designated place (CDP) in the towns of Schodack and Nassau in Rensselaer County, New York, United States. It was first listed as a CDP prior to the 2020 census.
Nassau Lake CDP is in southern Rensselaer County, surrounding a lake of the same name. The CDP includes the hamlets of Rosecrans Park, Braeside, and Morey Park, and it is bordered to the south by the village of Nassau. The CDP is southeast of Albany, the state capital. The outlet of Nassau Lake, the Valatie Kill, flows south to Kinderhook Creek, which continues southwest to Stockport Creek and the Hudson River.
The Nassau Lake is currently polluted with PCBs, industrial hazardous waste and carcinogens from the Dewey Loeffel Landfill. In 2019, the Community Advisory Group was founded on the basis of communication about future plans regarding this lake and the pollution.[2]