How to evaluate innovations, especially in the beginning of new product development, is a question constantly posed by academics, managers, and policymakers. One reason for this is that improved front-end decisions greatly affect company performance. To find the answers to this question, this review article analyzes scientific publications on innovation indicators published between 1980 and 2015. The objective of this article is to increase the understanding of the indicator landscape and to complement the various stages of the innovation process with relevant indicators. In doing so, this study categorizes the identified indicators into company-specific and contextual dimensions. Furthermore, this study analyzes the indicators in terms of their potential for ex-ante and ex-post evaluation and investigates the characteristics of relevant publications. The analysis finds that more process rather than product indicators exist in the literature. Current publications emphasize qualitative and indirect indicators but neglect indicators for the early stages of the innovation process. The review identifies 82 unique indicators to evaluate innovations including 26 indicators for the early stages. The results can help managers, researchers, and policymakers to better understand the innovation process and the indicator landscape. However, more concrete indicators are needed to improve front-end innovation decisions.