Machine wash in cold water with like colors. Air dry preferred, tumble on low temperature acceptable.
Why air dry preferred? Using any amount of heat to dry leggings can cause the fabric to shrink unevenly. Air drying ensures consistent drying while also being a no heat method. Tumble dry on low temperature helps prevent uneven shrinking, but doesn't guarantee that the leggings retain their original shape.
Do not iron. Do not bleach. Do not dry clean.