Socioscientific issues (SSI) are emerging issues globally nowadays, and at the same time,become an important research field in science education internationally. Accordingly,teaching and learning of SSI and the related skills of inquiry and argumentation arerecognized in school science today. This study is based on the EU FP7 project PARRISE (No.612438) aiming to promote socioscientific inquiry-based learning (SSIBL). In addition to thedesign of the six-step SSIBL teaching module shown in this presentation, the study aims toinvestigate how students’ knowledge and values interact in students’ SSI-decision-making. Atotal of seven students (4 males and 3 females) from a science-major program at an uppersecondary school in Sweden were invited to participate in the SSIBL teaching module onenvironmental toxins in fish from the Baltic Sea. The findings showed that, even though thestudents were aware of the risks of eating fatty fish from Baltic Sea, still, two distinct groupsof SSI-decisions could be identified. For those who agreed that Sweden should have apermanent exemption from the EU regulation for dioxins in fatty fish from the Baltic Sea, themain arguments were connected to values and the reasons related to the consumers’ right offree choice and responsibility to keep informed about the risks. The further implication toresearch and education on enhancing SSIBL will be discussed at the presentation.