Breast cancer patients must often decide between multiple adjuvant therapy options to prevent cancer recurrence. Standard practice, as implemented in current decision support tools, is to present information about all options simultaneously, but psychology research suggests that sequential decision processes might improve decision making. We tested whether asking women to consider hormonal therapy and chemotherapy separately would improve women's risk knowledge and/or affect treatment intentions. We conducted an Internet-administered experimental survey of a demographically diverse sample of 1,781 women ages 40-74. Participants were randomized to experience a standard, comprehensive decision process versus sequential (one at a time) decisions regarding adjuvant therapy options for a hypothetical breast cancer patient with an estrogen receptor-positive (ER+) tumor. We assessed comprehension of key statistics, perceptions of treatment effectiveness, and perceived interest in adjuvant chemotherapy, as well as participants' numeracy levels. When participants made sequential decisions, they demonstrated greater comprehension of decision-relevant risk statistics, as compared to when they made decisions all at once (all P's < 0.001). Among higher-numeracy participants, those making sequential decisions were less interested in chemotherapy (P < 0.001). Lower-numeracy participants who considered all options simultaneously were insensitive to the degree of risk reduction, but those who made sequential decisions were sensitive (P = 0.03). In conclusion, presenting adjuvant therapy options sequentially improves women's comprehension of incremental treatment benefit and increases less numerate women's sensitivity to the magnitude of the achievable risk reduction over standard, all at once approaches. Sequential approaches to adjuvant therapy decisions may reduce use of chemotherapy among those at low risk for recurrence.