The present article is concerned with the theoretical foundations and practical aspects of developing pictorial scales. It aims to assess the potential of pictorial scales compared to verbal scales. The article provides a review of existing pictorial scales with a view to identifying suitable methodological approaches for developing such scales. The review showed that the development and especially validation of many pictorial scales did not follow a stringent methodological approach. A category system is proposed, which allows the classification of different types of pictorial scales. Finally, we present a first draft of a theoretical framework, which can provide guidance for the future development of pictorial scales. The present work carries the implication that a specific methodological approach is needed, which focuses more strongly on the particular needs of designing pictorial scales (e.g., testing the comprehensibility of pictures).