The premise that emotions influence decisions is widely accepted, but relatively few studies have directly measured or manipulated emotional variables during decision making. This chapter surveys the current literature on this topic. Emotion modulates choices through two main routes. The first is through incidental affect, in which a baseline affective state can shift choices, although it is unrelated to the decision. This can be assessed through techniques such as stress or mood induction, and affective priming. The second way emotion can influence decisions is by being directly incorporated into the value computation during choice. For example, it has been shown that physiological arousal responses to the choice options or outcomes are linked to decisions. If we can characterize how emotion modulates choices, then we should also be able to alter choices by changing emotional states. We discuss how techniques such as emotion regulation and targeting memory reconsolidation might flexibly modulate choice.