The question “why some people, and not others, discover and exploit those opportunities” (Shane & Venkataraman, 2000: 218) is still one of the core questions in entrepreneurship research. As starting a new business is generally perceived to be a high-risk activity, entrepreneurs have long been regarded as being risk-takers. Yet, though some authors identified significant relationships between entrepreneurs and the propensity to take risks, results were often inconsistent or contradictory. Hence, the attitude towards risk taking amongst entrepreneurs has not been shown to be different from other people. Though, a fair amount of research about entrepreneurial risk taking has been done before, there is––as far as to our knowledge––no study to date that explicitly contrasts both heuristic biases optimism and overconfidence in their effects on entrepreneurial decision-making behavior under risk. Our paper addresses this gap.