The invention includes methods of forming patterns in low-k dielectric materials by contact lithography. In a particular application, a mold having a first pattern is pressed into a low-k dielectric material to form a second pattern within the material. The second pattern is substantially complementary to the first pattern. The mold is then removed from the low-k dielectric material. The invention also includes a method of forming a mold; and includes a mold configured to pattern a mass over a semiconductor substrate during contact lithography of the mass.