In this correlational study, 203 people from Germany, 144 women, 57 men, and two diverse participated. One hundred thirty-seven were omnivores, and 65 were vegetarians/vegans; one person did not answer this question. Participants were recruited through newsletters and social media from the participating universities. If they were students at the participating university, they got course credit. However, the participant’s name could not be linked to the data. For Hypothesis 1, medium effect sizes for the correlations (r = .3) between character strengths and the three sustainable behavioral consumption categories are assumed. Due to multiple tests, p was Bonferroni corrected and set to .002. The power analysis (power of 1-ß = .80) resulted in N = 145 participants (Faul et al., 2007). For Hypothesis 2, a power analysis for the linear regression resulted in N = 172 (Faul et al., 2007) assuming a medium effect size of f² = 0.15, an alpha level of p = .05, a power of 1-ß = .80 and 25 possible predictors for the dependent variable sustainable behavior regarding clothes, food, and in general (24 character strengths and diet preference).

The survey was set in an online tool for questioning, SoSciSurvey (Leiner, 2019). The link to the study was provided to the students at the respective universities and via social media. First, all participants gave their informed consent. Then, they filled out the socio-demographic questionnaire, the character strengths questionnaire, and the questionnaires of sustainable measurement. The study with the sample size calculation and the analysis plan was preregistered at OSF (see Jansen et al., 2022); all data can be found there. In an exploratory manner, we investigate if the character strengths and virtues differ between vegetarians/vegans and omnivores (see Jansen et al. (2025a) in the Supplementary Materials). Furthermore, the study was conducted according to the ethical guidelines of the Helsinki Declaration and approved by the Ethics Research Board of the University of Regensburg (No. 22-3059-101).

First, the correlation between the 17 character strengths (bravery, creativity, curiosity, forgiveness, gratitude, hope, humor, judgment, kindness, love, love of learning, perseverance, perspective, prudence, social intelligence, spirituality, zest) was calculated with a reliability > = .70, and the two questionnaires on sustainable behavior. Second, two multiple stepwise hierarchical regressions with sustainable food and clothes criteria were conducted. In the first block, diet preference was included as a predictor because it has been shown that the explicit attitudes towards vegetarian compared to meat-based food depend on their diet (Siebertz et al., 2022). The 17 character strengths were included as predictor variables in the second block.

The relationship between kindness and love of learning towards both types of sustainable behavior is in line with the results of the study by Valor et al. (2020). Kindness describes the values of care, compassion, and generosity (Park et al., 2004), which could be included in the prosocial behavior concept related to sustainable behavior (Otto et al., 2021). Love of learning comprises the mastery of new skills and the ability to systematically add further information to what one knows (Park et al., 2004). The result is also in line with a study by Jansen, Rahe et al. (2024), which showed that love of learning correlates to explicit attitudes towards vegetarian and vegan food, but only for omnivores. For the vegans and vegetarians, the implicit attitudes towards vegetarian and vegan food were positively correlated with the character strength of love of learning. Besides this, curiosity and zest were related to sustainable behavior but not relevant correlational factors in the study of Valor et al. (2020). Curiosity describes the need for an information search to close a knowledge gap (Loewenstein, 1994). Zest describes the ability to approach life with excitement and energy (Park et al., 2004). Both character strengths are related to openness to new experiences, and openness is related to sustainable behavior (Song & Kim, 2018). There are different facets within the concept of openness, and the facet of intellectual curiosity is consistently associated with pro-environmental attitudes and behaviors (Markowitz et al., 2012).

However, when entering the character strengths and the diet preference in both regression models, curiosity was relevant in both models. Curiosity is essential to acquire new knowledge about the sustainable behavior of food and clothes. Prudence means to be aware of the extended consequences of one’s actions. Choosing a vegetarian or vegan diet means considering the implications for your health and the planet. The negative prediction of the character strength of spirituality on sustainable food consumption is difficult to explain — people with high scores in spirituality report lower sustainable food consumption. Even this seems contradictory; it is in line with the result that vegetarians and vegans show a lower value of spirituality than omnivores (see Jansen et al. (2025a) in the Supplementary Materials). Because animal welfare, health, and environmental reasons were the most dominant motivators for a vegetarian diet within developed Western nations (Rosenfeld, 2018) and also in Germany (Janssen et al., 2016), where this study has been conducted, the reasons for sustainable food behavior are more rational than spiritual in this specific sample.

Kindness was a significant predictor of sustainable clothing consumption. This aligns with the study of Geiger and Keller (2018), which demonstrated a relation between compassion and the willingness to pay for fair-trade clothes. Kindness and compassion are both prosocial constructs, though it was indicated that kindness and compassion result from separable motivation systems differing in their emotional reaction and resulting actions (Kirby et al., 2022).

In some respects, this study’s results differ from those of Corral Verdugo et al. (2015), Valor et al. (2020), and Diessner and Niemiec (2023). Reasons for this could be the different measurements of sustainable behavior and the various analysis methods in the few studies on the relation between character strengths and sustainable behavior. Some studies use composite scores to investigate sustainable behavior (e.g., Valor et al., 2020) or the Pro-Environmental Behavior Scale, where participants had to indicate how frequently they engaged in 12 pro-environmental behaviors during the past year (Diessner & Niemiec, 2023). The result of the study of Diessner and Niemiec (2023), which showed that appreciation of beauty and excellence is essential for pro-environmental behavior, could not be replicated because this character strength shows low reliability in this study. In contrast to the former studies, this study here differentiates, according to the model of Geiger et al. (2018), between two areas of sustainable behavior.

The study hints that internal transformative qualities like character strengths might be relevant to sustainable behavior. However, the few existing correlational studies have different results regarding which character strength is related to which type of sustainable behavior, which limits the conclusive evaluation of the importance of character strengths for sustainable behavior. One reason for these different results might be the various measurements of sustainable consumption behavior. A methodological study that compares the different measurements and validates the essential components would be needed. Furthermore, studies on the relationship between character strengths and sustainable behavior are conducted in various countries. Central cultural value orientations like collectivism, femineity, future orientation, and uncertainty avoidance can influence sustainable consumption (Chwialkowska et al., 2020). Besides, a possible cultural effect of the VIA should be discussed. Seven of the 24 character strengths show low internal consistencies, which contradicts the study of Corral Verdugo (2012) in a Mexican sample.

The relevant character strengths for sustainable behavior towards food and clothes were kindness, love of learning, curiosity, and zest. Hence, we suggest emphasizing those character strengths without neglecting the others because the results depend on measuring sustainable behavior. For example, simple shifts can be made in daily life to strengthen the character strength of kindness, like smiling from the heart to others and appreciating other people. But there is also a link to environmental design. Biophilic design might lead to improved character strengths like a love of learning, so it has been shown that students in classrooms with a natural view are more positive in rating the course than students in a course with a view of a concrete retaining wall (Benfield et al., 2015).

Because the explained variance of sustainable behavior is 19%–31%, relevant predictors of sustainable behavior, like personal and social norms or habits and attitudes, should be included in further studies (Klöckner, 2013).

The study is limited because seven of the 24 character strengths showed low reliability. Nevertheless, emphasizing measurement efficiency over internal consistency can be sufficient using short scales (Ziegler et al., 2014). Furthermore, the percentage of participating men and women, vegetarians/vegans, are different. Besides this, in future studies, the reasons for executing sustainable behavior concerning food and clothing, the possible gratification and social reward, and the costs of carrying out this consumption behavior for behaving sustainably should be included in the analysis. The study presented here is a starting point for further investigations on the various factors of internal transformative qualities (connection, awareness, insight, purpose, and agency) and different dimensions of sustainable consumption behavior.