Penelitian ini bertujuan untuk mendeskripsikan keefektifan dan membandingkan keefektifan problem solving setting team assisted individualization (TAI) dengan guided inquirysetting TAI ditinjau dari prestasi belajar, kemampuan berpikir kritis, dan kedisiplinan diri siswa. Populasi penelitian ini adalah seluruh siswa kelas VII SMP Negeri 1 Lebaksiu yang terdiri atas 9 kelas. Dari populasi yang ada diambil secara acak dua kelas, yaitu kelas VII H dan kelas VII I sebagai sampel kelas penelitian. Kelas VII H diberi treatment dengan pendekatan pembelajaran problem solving setting TAI, sedangkan kelas VII I dengan guided inquiry setting TAI. Data dianalisis dengan menggunakan uji one sample t-test, uji MANOVA dengan T2 Hotteling’s dilanjutkan dengan uji t-Benferroni untuk menentukan pendekatan pembelajaran mana yang lebih efektif. Hasil penelitian menunjukkan bahwa pendekatan pembelajaran problem solving setting TAI dan guided inquiry setting TAI keduanya efektif ditinjau dari prestasi belajar, kemampuan berpikir kritis, dan kedisiplinan diri; pendekatan pembelajaran guided inquiry setting TAIlebih efektif daripada problem solving setting TAI ditinjau dari masing-masing aspek. Kata Kunci: problem solving, guided inquiry, team assisted individualization, prestasi belajar, kemampuan berpikir kritis, kedisiplinan diri   The effectiveness of problem solving and guided inquiry viewed from students’ learning achievement, critical thinking skills, and self-discipline   Abstract This study aims to describe the effectiveness and compare the effectiveness of problem solving in team assisted individualization (TAI) setting with guided inquiry in TAI setting viewed from the students’ learning achievement, critical thinking skills, and self-discipline. The research population comprised all Class VII students, consisting of 9 classes of SMP Negeri 1 Lebaksiu. From the population, two groups (classes), class VII H and class VII I, were selected randomly as the research class sample. Class VII H was treated with the approach of learning problem solving in TAI setting, while class VII I was treated with the guided inquiry in TAI setting. The data were analyzed using one sample t-test, MANOVA with T2 Hotteling’s and then continued by t-Benferroni test to determine which the approach of learning is more effective. The results of study show that the approaches of learning problem solving in TAI setting and guided inquiry in TAI setting are both effective viewed from students’ learning achievement, critical thinking skills, and self-discipline, and the approach of learning guided inquiry in TAI setting is more effective than problem solving in TAI setting in terms of each aspect. Keywords: problem solving, guided inquiry, team assisted individualization, learning achievement, critical thinking skills, self-discipline