Filipino students generally exhibit low critical thinking skills and scientific attitudes, necessitating innovative educational strategies to address this gap. This study examines the effectiveness of Modified Inquiry Learning Strategies, specifically the Inquiry Investigation Group (IIG) strategy and the InREACT strategy, in improving critical thinking skills and scientific attitudes. Conducted with 86 Grade 8 students from Nabangka National High School, Guinayangan, Quezon, during the school year 2023-2024, the research employed a pretest-posttest experimental research design. Data were collected through pre- and post-assessment tests on critical thinking skills and scientific attitudes, supplemented by surveys. Statistical analysis, including ANOVA, evaluated the differences in scores. The results showed significant improvements in students critical thinking skills, particularly in interpretation and analysis, and notable enhancements in scientific attitudes, including rationality, open-mindedness, faith in science methods, curiosity, and aversion to superstitions. There were significant differences in post-assessment scores for critical thinking skills and scientific attitudes between students exposed to the modified inquiry strategies and those using conventional strategies. These findings demonstrate that modified inquiry learning strategies effectively enhance cognitive engagement and foster a positive disposition toward science. The study underscores the importance of integrating these strategies into educational practices to improve students critical thinking abilities and scientific attitudes.