The Severn Valley Railway line is offering the chance to buy shares in the company in a bid to raise £3million.
Shares go on sale from today as part of a drive to raise money for future projects on the heritage line.
People will be able to buy shares priced at a pound each - but there is a minimum investment of £100 required.
It needs the money for a "major investment" that will happen over the next 50 years.
The attraction, that runs between Shropshire and Worcestershire, is looking to improve its Bridgnorth station, add a visitor centre, maintain its tracks and train young people in the up-keep of a heritage railway.
The line carries about 250,000 passengers a year and is run by volunteers and enthusiasts passionate about steam engines.