Two reserve leagues comprising 27 clubs will operate in the coming season, the Scottish Professional Football League has confirmed.
These will replace the development leagues, in place since 2009.
The SPFL steering group is "of the view that it would benefit the development of young players if they were playing alongside more experienced players on a more regular basis".
Other than a minimum age of 16, no age restrictions will apply to the leagues.
The SPFL says the changes "complement recent amendments to loan regulations which provide, generally, that any player loaned out by an SPFL club is eligible to return and play in non-first team football for the lending club".
The top tier of the new reserve league features 18 clubs, who will play each other once in a 17-match season, with fixture generally being played on Monday afternoons.
The second-tier Reserve League 2 comprises nine clubs, who will play each other once at home and once away for a total of 16 matches across the season. These fixtures will take place on midweek evenings.
The first division reserve league is due to begin on 20 August, with the second tier league kicking off the following midweek.
The SPFL will also introduce divisional Reserve League Cups "to provide additional games during the season". It says the format will follow the Scottish League Cup, whereby any drawn group matches will proceed to penalties with an additional bonus point available.
Reserve League clubs:
Aberdeen, Celtic, Dundee, Dundee United, Dunfermline Athletic, Falkirk, Hamilton Academical, Heart of Midlothian, Hibernian, Kilmarnock, Morton, Motherwell, Partick Thistle, Queen of the South, Rangers, Ross County, St Johnstone, St Mirren.
Reserve League 2 clubs:
Airdrieonians, Albion Rovers, Ayr United, Berwick Rangers, East Kilbride, Livingston, Queen's Park, Raith Rovers, Stirling Albion.