On the label it says “Worsted Spun Fine Wool”, made from 100% merino top.
From Stonehedge Fiber Mill’s web site: “The three-ply yarn is spun to 1000 yards per pound, which in 4-ounce skeins is 250 yards per skein. It knits like any commercial worsted weight yarn, about 5 stitches to the inch on size 6-8 needles. This yarn is worsted spun, meaning it’s very very smooth and almost shiny in appearance. It will give great stitch definition for intricate patterns such as lace, cables, and knit/purl patterns.”
Care: hand wash; do not agitate.