First article in a series on twills from Master Weaver, No. 67. It explains how 2:2 twill develops from 2:2 basket weave and describes the notation for float lengths (2/2, 3:1:1:2). It also covers twill classes: balanced, biased, reversible, warp-face and weft-face, and LH and RH diagonals. It lists reversible and non-reversible twills up to 8 shafts, warns about false twills, and suggests drawing down the listed twills as an exercise.