Our case describes the application of extended focus group interview as a method of exploration preceding experimental and quantitative verification within a mixed method project. Overall, we aimed to understand how consumers interpret colors of nutrition labels in the context of consumers’ product healthfulness criteria across different product categories. The meaning of colors turns out to be a complex, highly subjective, and contextual phenomenon, rarely discussed in a previous literature on usage of colors in nutrition labeling systems. Thus, we applied the qualitative method to explore the subjective criteria of product healthfulness and to understand how consumers perceive, evaluate, and make inferences about product healthfulness based on colors which are used in selected food labeling systems and how their associations depend on the context (e.g., type of products, presence of other colors, words, or figures). Focus group interviewing enabled us to gain insight into spontaneous inferences and to obtain a wide picture of consumers’ opinions. Longer time of the interview (2 hr 45 min), which distinguishes extended groups from other types of focus groups, provided opportunity of measurement of reactions toward many stimuli materials within consumers’ existing structures of subjective experience and knowledge. In the case, we present how we made decisions about the method choice and participants’ selection within budget limitation, how we developed the discussion guide regarding the natural process of group dynamic, and how we dealt with analysis of 70 pages of transcript through process of coding and displaying data in a table matrix.