What is expression in music? As a conductor, how do you interpret music? This chapter investigates the important principles of interpretation and expression in Western repertory and provides conducting gestures to achieve your expressive goals. The first section, both philosophical and practical, attempts to articulate the ineffable, that is, to present verbally and objectively complex information that is inherently intuitive, feelingful, and creative. The second section applies theory to practice, developing expressive gesture through left-hand technique. Although you may use the left hand on occasion to mirror and reinforce the right hand in beat patterns, fermatas, preparations, and releases, it must function as an independent and expressive conducting instrument for shaping phrases, giving dynamics, balancing parts, cuing, and the like.