| Montague | |
| Official Name: | Township of Montague |
| Settlement Type: | Township (lower-tier) |
| Pushpin Map: | Canada Southern Ontario |
| Pushpin Map Caption: | Montague within southern Ontario |
| Subdivision Type: | Country |
| Subdivision Name: | Canada |
| Subdivision Type1: | Province |
| Subdivision Name1: | Ontario |
| Subdivision Type2: | County |
| Subdivision Name2: | Lanark |
| Government Type: | Township |
| Leader Title: | Reeve |
| Leader Name: | Karen Jennings |
| Leader Title1: | Governing Body |
| Leader Name1: | Montague Township Council |
| Leader Title2: | MP |
| Leader Name2: | Scott Reid (CPC) |
| Leader Name3: | John Jordan (PCPO) |
| Established Title: | Incorporated |
| Area Total Km2: | 279.66 |
| Population As Of: | 2016 |
| Population Footnotes: | [1] |
| Population Total: | 3761 |
| Population Density Km2: | 13.4 |
| Timezone: | EST |
| Utc Offset: | −05:00 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | −04:00 |
| Postal Code Type: | Postal code span |
| Area Code: | 613, 343 |
| Coordinates: | 44.9667°N -133°W |
Montague is a township in eastern Ontario, Canada, in Lanark County on the Rideau River. The township administrative offices are located on Roger Stevens Drive east of Smiths Falls.
The township comprises the communities of Andrewsville, Atironto, Kilmarnock, Nolans Corners, Numogate, Poolers Corners, Rosedale and Welsh.
In the 2021 Census of Population conducted by Statistics Canada, Montague had a population of living in of its total private dwellings, a change of from its 2016 population of . With a land area of 278.47km2, it had a population density of in 2021.[2]
The main roads in the township are the east–west County Road 43, the north–south Ontario Highway 15, and the northeast-southwest Roger Stevens Drive. The Rideau Trail passes through the township between Merrickville and Smiths Falls.