Based on the Trends in International Mathematics and Science Study 2007 study and a follow-up national survey, data for 3,901 Taiwanese grade 8 students were analyzed using structural equation modeling to confirm a social-relation-based affection-driven model (SRAM). SRAM hypothesized relationships among students' perceived social relationships in science class and affective and cognitive learning outcomes to be examined. Furthermore, the path coefficients of SRAM for high- and low-achieving subgroups were compared. Given the 2-stage stratified clustering design for sampling, jackknife replications were conducted to estimate the sampling errors for all coefficients in SRAM. Results suggested that both perceived teacher-student relationships (PTSR) and perceived peer relationships (PPR) exert significant positive effects on students' self-confidence in learning science (SCS) and on their positive attitude toward science (PATS). These affective learning outcomes (SCS and PATS) were found to play a significant role in mediating the perceived social relationships (PTSR and PPR) and science achievement. Further results regarding the differences in SRAM model fit between high- and low-achieving students are discussed, as are the educational and methodological implications of this study.