The objective of this study was to investigate the substantive aspect of construct validity of the Satisfaction with Life Scale adapted for Children (SWLS-C; Gadermann et al. in Soc Indic Res 96:229-247, "2010"). Specifically, the study examined the cognitive processes of children when responding to the items of the SWLS-C to find out how they interpret and respond to the items. Think-aloud protocol interviews were conducted with 55 students in grades 4-7 (58% girls, mean age of 11 years, ranging from 8.8 to 12.8 years) and content analysis was used to analyze the data. The findings indicate that most children had no difficulty in understanding the items, and used mainly two strategies for responding to the items: (1) an absolute strategy, in which children used absolute statements to indicate the presence or absence of something that is important for their judgment of their satisfaction with life, and (2) a relative strategy, in which children used relative or comparative statements. In the absolute statements, children primarily referred to social relationships, personal characteristics, time use, and possessions. In the relative statements, the children primarily compared what they have to (a) what they want (b) what they had in the past, (c) what other people have, and (d) what they feel they need. Furthermore, most children considered it important that information on their life satisfaction is obtained. The results are discussed with regard to multiple discrepancies theory (Michalos in Soc Indic Res 16:347-413, "1985") and previous empirical findings. The results provide insights into children's cognitive processes when responding to items on life satisfaction and provide validity evidence that the SWLS-C is an appropriate measure to assess life satisfaction in children of this age.