The traditional
Belted Plaid also called the Great Kilt, is the precursor
of the modern kilt, but the two are not at all the same thing.
The modern kilt is essentially a tailored skirt with sewn
pleats, leather straps and buckles, and is worn for ceremonies,
parades and military demonstrations. The modern kilt really
has no place in historical reenactments of any period prior
to the late 18th century.
Most historians agree that the Great Kilt developed into its belted and
draped form during the late 16th to early 17th century, possibly evolving
from a simple cape or blanket worn over the shoulders in the style
of the Irish Brat. (The Scots were Gaels who emigrated from Ireland
in the 5th and 6th centuries to what was then Pictish Caledonia). So,
despite what we see in Braveheart, William Wallace, who died in the
early 14th century, would not have worn the Belted Plaid, although
he could have worn, simply, a plaide, which is the Gaelic word for
blanket.
To Begin: The Great Kilt begins as nothing more than a rectangular length
of woolen plaid, also called a tartan. Unfold your tartan and lay it flat
in an open area. Working from one of the short ends of the rectangle, slide
a wide leather belt under it lengthwise, inside up, approximately in the
middle. If you plan to hang a dagger sheath or other implements from the
belt, be sure to have already slid them on. Place your elbow at the same
edge of the tartan (just below the belt buckle) and measure a forearm’s
length (an ell). The ell will not be pleated, but will fall as part of
the front “apron” once the kilt is completed.
The Pleating:
Working on one side of the belt only, (the other side will
be draped and need not be pleated) place your two thumbs
at the far end of the ell and measure a thumb to fingertip
span. Pinch the span of cloth into a pleat by pulling it
toward you. Then move your thumbs to the other side of the
fold and continue pleating in this manner until you have
a second ell remaining at the other end. When complete, the
pleated tartan will shrink up to a few feet in length.
The Wrapping:
Lay your man down – gently — on the tartan so
that the pleated edge hits about the tops of his knees. Pull
the right apron over and across the hips (careful not to
undo the pleats), and then the left, overlapping the two.
You should be able to find the other end of the belt now.
Adjust the belt to the waist and secure snugly.
*The Draping
and Pinning: Stand up. The pleated skirt will be hidden beneath
the unpleated portion of the plaid, which will hang to the
ankles all around. Lift the front corner of the top-most
layer, wrap it around to the back (giving it a twist or two,
if desired) and tuck it into the belt. Lift the corner of
the remaining unpleated layer in front, together with the
end of the fabric now draped in the back, and join the two
at the shoulder. Pin with a large brooch, called a pennanular,
and/or use a leather tie. Pin the aprons closed in front
with a large blanket pin, or fibula, and/or wear a sporran
(but make it a leather one, not the more modern fur-trimmed
kind). The Great Kilt can be worn over either shoulder, although
it is advisable for right-handed warriors to wear it on the
left shoulder, and vice versa, to better facilitate the wielding
of weapons.

* My research
suggests there is no right or wrong way to drape a kilt.
The style described here is the one typically seen in movies
as well as old paintings and sketches, and we like it. Another
option is to tuck both corners in back, and then pin the
fabric up on one shoulder, resulting in little or no draping
in front or to the side. Or, for wintry days, don’t
tuck either layer into the belt, but draw the fabric up from
behind you and drape over both shoulders like a cape, and
pin closed. Try experimenting. It's all a matter of personal
preference.