This paper reviews current research relevant to new product development, customer development, and the lean startup. Customer development and the lean startup are a new and increasingly used form of entrepreneurship process, which rely on hypothesis testing but not in the traditional sense; the entrepreneur is encouraged to scan the environment, collect information, and form and evaluate educated guesses so as to make accurate judgments and decisions. The present research provides a review of the customer development model for entrepreneurial activities and a critique of this hypothesis testing methodology. We then consider ways in which to improve decision making within the startup via a systematic study of System 1 ( intuition) and System 2 ( reasoned and rational) decision-making styles. This paper has significant implications for entrepreneurs, entrepreneurship support organizations, such as incubators and accelerators, and entrepreneurship educators, all of whom are increasingly practicing and teaching this process