| Official Name: | Lacy, Indiana |
| Pushpin Map: | USA Indiana Martin County |
| Pushpin Label: | Lacy |
| Pushpin Map Caption: | Location in Martin County |
| Mapsize: | 120px |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Indiana |
| Subdivision Type2: | County |
| Subdivision Name2: | Martin |
| Subdivision Type3: | Township |
| Subdivision Name3: | Halbert |
| Timezone: | Eastern (EST) |
| Utc Offset: | -5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | -4 |
| Coordinates: | 38.6336°N -86.7764°W |
| Elevation Ft: | 614 |
| Postal Code Type: | ZIP code |
| Postal Code: | 47581 |
| Area Code: | 812, 930 |
| Blank Name: | FIPS code |
| Blank Info: | 18-40680[1] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 451128 |
Lacy is an unincorporated community in Halbert Township, Martin County, in the U.S. state of Indiana.
A post office was established at Lacy in 1901, and remained in operation until it was discontinued in 1904.[2]