The aim of this study was to investigate the effect of Science-Technology-Society (STS) curriculum on students' scientific literacy, problem solving and decision making. Four hundred and eighty (480) Senior Secondary two science and non-science students were randomly selected from intact classes in six secondary schools in Calabar Municipality of Cross River State. The experimental and control groups each comprised 120 science and 120 non science majors randomly assigned to them. The experimental group was exposed to researcher designed and validated Curriculum in Science-Technology-Society (COSTS) for 24 weeks at 2 h per week. The control group followed the normal existing science curriculum. A quasi experimental factorial design was used to identify the effect of COSTS if any scientific literacy, problem solving and decision making ability in coping with socio-scientific issues. The Test on Science-Technology-Society (TOSTS) was administered to both experimental and control groups. The data obtained were subjected to statistical analysis using covariance and the result emerged that students taught using the COSTS performed significantly better in scientific literacy, problem solving, and decision making than students who were not exposed to COSTS materials. This study highlights the need for an alternative science curriculum that will make students to be scientifically literate, problem solvers, and rational decision makers in a society riddled with science and technological problems. (Contains 5 tables.)