Global challenges such as climate change, ecosystem loss, and pollution demand that education systems promote environmental knowledge and values aligned with the Sustainable Development Goals. The Trends in International Mathematics and Science Study (TIMSS) 2023 contributes to this effort by complementing mathematics and science assessments with questionnaires on students’ environmental attitudes and behaviors. This chapter explores patterns of environmental knowledge and pro-environmental values among fourth- and eighth-grade students in Albania, Austria, Bosnia and Herzegovina, the Czech Republic, Hungary, the Slovak Republic, and Sweden, while also considering national sustainability achievements. Using a descriptive approach, TIMSS 2023 data is analyzed alongside sustainability indicators to examine links between students’ socioeconomic background, knowledge, and attitudes. Results show a consistent relationship across all countries: students from higher socioeconomic backgrounds demonstrate stronger environmental knowledge, highlighting how social inequality shapes knowledge and pro-environmental attitudes. Students across countries show limited success on tasks addressing key environmental issues, especially those insufficiently addressed in their national context. Nonetheless, some countries achieve comparatively higher results, suggesting that curriculum design and implementation play a significant role in fostering success. These findings confirm trends identified in earlier research while also providing new insights into the interplay between socioeconomic status, environmental knowledge, and values.