The Queen is due to present new colours to The Royal Regiment of Scotland, later.
Her Majesty will present the colours to the six battalions of The Royal Regiment of Scotland for the first time since the regiment's formation five years ago.
The regiment will then march through Edinburgh.
The occasion marks the first time six battalions from any regiment have been on parade at the same time.
The parade, which will include marching contingents from six of the seven battalions of The Royal Regiment of Scotland, will take place in Holyrood Park.
The 4th Battalion is currently deployed on operations in Afghanistan.
The parade will also include several hundred veterans from the regiment's antecedent units.
The Queen has been Colonel-in-Chief of The Royal Regiment of Scotland since its formation in 2006.
Colours are important to any army unit.
They consist of two large brocade and embroidery flags and were originally carried into battle so that soldiers of a particular unit could see where the rest of their unit was located at all times.
The infantry units of the British army each have two colours; the Queen's Colour, which is a union flag, and a Regimental Colour, which has all the unit's battle honours inscribed on it.
Colours are no longer carried on the battlefield but are held in the greatest esteem by the soldiers and officers.
They are brought out on important parades and regimental occasions and are escorted by a 'colour party'.
When new colours are presented, the old ones are not destroyed but are laid up in a regimental museum, church or other military building with significance to its particular unit.
Colours are normally presented only every 20 to 25 years.
The Royal Regiment of Scotland consists of seven battalions, five regular and two territorial army.
One of these was formed by the amalgamation of the Royal Scots and King's Own Scottish Borderers, while the others are each formed from one of the remaining single-battalion regiments of the Scottish division.
Along with The Rifles, it is currently the largest infantry regiment in the British army.