On 22 July 1978, an LMS Class 2MT locomotive numbered 46464 - 'The Carmyllie Pilot' - hauled the first preserved passenger service on the line. The train left Aviemore Speyside station, ran the short distance to Boat of Garten, and brought half a century of British railway preservation history to the Spey valley. Locomotive 46464 was built at Crewe Works in 1950, one of a class of small mixed-traffic 2-6-0 engines designed by H.G. Ivatt for the London, Midland and Scottish Railway. By 1978 it was rare and irreplaceable. The Strathspey Railway has since acquired a working fleet that includes sister engine 46512 (built at Swindon in 1952), the unique Caledonian Railway 0-6-0 number 828 (built in 1899 and one of only two surviving Caledonian engines in working order), and the Andrew Barclay industrial saddle tank 'Braeriach', built in Kilmarnock in 1935. The four-road locomotive shed at Aviemore was built by the Highland Railway in 1898 to serve trains heading for Perth, Inverness, and Forres. It still does.

The line uses British Railways mechanical semaphore signalling - the arms-and-wires system that has almost vanished from the modern railway. Signals are pulled by levers in two physical signal boxes at Boat of Garten, one at the north end and one at the south. The single-track section from Boat of Garten South to Aviemore Speyside is controlled by Electric Key Token; the section from Boat of Garten North to Broomhill is still worked by Staff and Ticket, the older system that depends on a physical token carried with the train. Train crews coal their locomotives at a facility built in 2014 on the site of the former Aviemore Speyside station. Spey Lodge, a hostel built by the LMS during the Second World War to accommodate engine crews working away from home, now does the same job for volunteers. The level crossing at Dalfaber was added in the 1980s when housing arrived on the line's edge. Almost everything else is original or deliberately reconstructed in period style.

Halfway along the line, the train pulls into Boat of Garten. The station building dates from 1904 - a category B listed structure designed by William Roberts, with its original booking hall, ticket office, and waiting room still in use. The waiting room has an open fire. A coffee shop now occupies the old gas house on platform 1. The station was originally the junction where the Highland Railway main line from Perth to Forres met the Great North of Scotland Railway branch to Craigellachie; the GNSR's branch was the original Strathspey Railway, a name the preserved line now carries. The yard behind the station stores the majority of the railway's out-of-service rolling stock, and a new covered shed built in 2018-2019 keeps the wooden carriages out of the weather. Boat of Garten is also the only place on the line with a water column. When a locomotive needs to drink, this is where it stops. The village outside is known to ornithologists as the Osprey Village - Loch Garten and its famous nest sit just a short walk away.

The northern terminus, Broomhill, sits in countryside roughly halfway between Nethy Bridge and Dulnain Bridge. The replica station building stands on the foundations of the original. Viewers of the BBC drama Monarch of the Glen, which ran from 2000 to 2005, will recognise it as Glenbogle, the fictional Highland railway station that featured throughout the series. The volunteers' ambition stretches farther: a full extension to Grantown-on-Spey along the original Highland Railway alignment to Dava and Forres. The Scottish Executive committed in 2006 to re-aligning the A95 at Gaich to allow the railway to pass underneath, and donated trackwork from the relaid Stirling-to-Alloa line is waiting in storage. Network Rail donated the steelwork of the former Merry Street Bridge in Motherwell; in February 2014, with Colas Rail providing one of the few cranes in Britain capable of the lift, the bridge was installed over the River Dulnain and track was laid across it. The full extension would cost more than £13 million and depends on Scottish Government statutory orders that have not yet arrived. For now, the train chuffs out beyond Broomhill into the fields, the locomotive changes ends on the passing loop, and it returns south.