Little Devil Peak forms the south end of a moderately high ridge running generally south to north on the western edge of North Cascades National Park near Marblemount.
The average altitude of the ridge crest, called Teebone Ridge due to its shape, is just under 7000 feet, but the ridge, like so many other places in the North Cascades, offers very large relief, in this case about 6500 feet down to the Skagit River in about five miles. This ridge is generally composed of fairly solid ancient metamorphosed granite plutons in the form of gneiss and schist, so unlike other places in the North Cascades, pleasant and easy alpine travel can be found here.
Little Devil cradles several small ice sheets and two small glaciers, generally on north-facing slopes, but somewhat remarkably the largest of them, the Monogram Glacier, lies in a deep, south-facing cirque south of the summit. This dying glacier has a small ice cliff calving off into a lake at its terminus.
From the crest of Teebone ridge and the summit proper expansive views of the heart of the Cascades from Rainier to the Olympics, and on into Canada await.
The first ascent of Little Devil was likely by a USGS party many years ago according to Fred Beckey in the Cascade Alpine Guide Volume 2.
Little Devil Peak can be accessed most reasonably from one of two directions.
1) The first is by far the easiest, shortest, and most direct. Begin by taking the Cascade River Road 6.4 miles East of Marblemount and starting at the Lookout Mountain Trailhead at about 1200 feet. This trail heads steeply uphill to a junction at about 4200 feet after 2.8 miles or so. The trail heading West leads to the summit of Lookout Mountain, and the trail leading East continues to Monogram Lake. Following the trail towards Monogram Lake brings one out into increasingly open slopes and gives easy access to the South side of Little Devil Peak.
2) The second option is to access the peak by traversing Teebone Ridge from the North over and around the other high points, the Trapezoid, Big Devil, Fallen Angel, and Baksit to a col SW of the summit of Little Devil. This will entail several miles of off-trail, subalpine travel to attain Teebone Ridge from Newhalem via the Newhalem Creek Road. Then several miles of alpine travel across broken rock, likely up to 4th class, ice, and snow to the base of Little Devil Peak.
Little Devil Peak lies in North Cascades National Park so free, but limited, permits are required to be picked up at the Wilderness Information Center in Marblemount for overnight stays. All cross-country campspots must, by NCNP rules, be one-half mile from any trail and one mile from any established camp.
Party size is limited to six "pairs of eyes," in any cross-country zone, and 12 on any trail in the national park. So a total of either six or 12 stock, people, and dogs are allowed in any given party.
It is not clear whether a Northwest Forest Pass is required to park at the Lookout Mountain Trailhead, but it lies on National Forest land so it is likely.
A designated campspot exists at Monogram Lake, and many people make camp at the Lookout Mountain summit. Above Monogram Lake, for the entirety of Teebone Ridge, durable surfaces can be found on which to sleep; try to use only established spots to protect vegetation.
This peak can be reasonably scrambled in a day.