The Reserve Leagues were brought in to replace the Development Leagues, and were the result of discussions held over an 18-month period by the Competitions Working Group.
Members of the group, including Scottish FA Performance Director Malky Mackay and representatives from all four SPFL tiers, felt younger players would stand a greater chance of progressing and developing if they were able to play alongside more experienced team mates on a regular basis.
Development League matches were contested by under-20 level teams, with five over-age players permitted in each matchday squad of 18.
Under the new system, the lower age limit for reserve matches is 16 with no restrictions on over-age players.
The first division of the Reserve League is made up of 18 clubs who will play each other once over a 17-match season. Fixtures will ordinarily take place on Monday afternoons.
The second tier, dubbed Reserve League 2, will see nine clubs play each other home and away over 16 matches, with fixtures taking place on midweek evenings.
Divisional cup tournaments will be introduced to raise the number of games played over the course of the campaign, with the format likely to mirror that of the Betfred Cup, in that any group games ending in a draw will be decided on penalties with a bonus point awarded to the victors.
Reserve League fixtures are expected to be published later this week, with the first games for the top tier scheduled for August 20, and the second division games kicking off a week later.
There are seven Scottish Championship teams in the top tier - Dundee United, Dunfermline, Falkirk, Morton, Partick Thistle and Ross County - while recently promoted Livingston are the only Premiership side in the second division.
Last year’s Lowland League runners-up East Kilbride will enter a team in Reserve League 2, while last season’s League One winners Ayr United will also compete in the second division.
Reserve League 1 clubs: Aberdeen, Celtic, Dundee, Dundee United, Dunfermline, Falkirk, Hamilton, Hearts, Hibs, Kilmarnock, Morton, Motherwell, Partick Thistle, Queen of the South, Rangers, Ross County, St Johnstone and St Mirren.
Reserve League 2 clubs: Airdrieonians, Albion Rovers, Ayr United, Berwick Rangers, East Kilbride, Livingston, Queen’s Park, Raith Rovers and Stirling Albion.