ABSTRACT Writing an observation report text requires students to develop ideas, organize information, and arrange it into a coherent text. This study analyzes the effect of the Think Pair Share (TPS) strategy on the observation report text writing ability of eighth-grade students at SMPN 1 Wanasaba in the 2026/2027 academic year. The study employed a quantitative approach using a quasi-experimental method and a Nonequivalent Control Group Design. A total of 62 students participated, consisting of 31 students from class VIII A as the experimental group and 31 students from class VIII B as the control group, selected through cluster random sampling. Data were collected through writing tests in the form of pretests and posttests, observations, and documentation, and were analyzed using descriptive statistics and an Independent Samples t-Test with the assistance of SPSS 23.0. The mean score of the experimental group increased from 62.68 on the pretest to 84.45 on the posttest, while the control group increased from 51.16 to 58.65. The analysis yielded t = 8.019, df = 42.494, and p = 0.000, indicating a significant difference in the posttest scores between the two groups. The magnitude of the difference was also reflected in a Cohen’s d of approximately 2.05. These findings indicate a large difference in achievement within the context of the two classes studied, although the interpretation should consider the difference in initial ability because the students were not individually randomized. ABSTRAK Kemampuan menulis teks laporan hasil observasi menuntut siswa mengembangkan gagasan, menata informasi, dan menyusunnya menjadi teks yang runtut. Penelitian ini menganalisis pengaruh strategi Think Pair Share (TPS) terhadap kemampuan menulis teks laporan hasil observasi siswa kelas VIII SMPN 1 Wanasaba tahun pelajaran 2026/2027. Penelitian menggunakan pendekatan kuantitatif dengan metode quasi-experimental dan desain Nonequivalent Control Group Design. Sebanyak 62 siswa terlibat, terdiri atas 31 siswa kelas VIII A sebagai kelompok eksperimen dan 31 siswa kelas VIII B sebagai kelompok kontrol yang dipilih melalui cluster random sampling. Data dikumpulkan melalui tes menulis pretest dan posttest, observasi, serta dokumentasi, kemudian dianalisis menggunakan statistik deskriptif dan Independent Samples t-Test berbantuan SPSS 23.0. Rata-rata kelompok eksperimen meningkat dari 62,68 pada pretest menjadi 84,45 pada posttest, sedangkan kelompok kontrol berubah dari 51,16 menjadi 58,65. Pengujian menghasilkan t = 8,019, df = 42,494, dan p = 0,000, sehingga terdapat perbedaan signifikan pada skor posttest kedua kelompok. Besarnya perbedaan juga tercermin dari Cohen’s d sekitar 2,05. Temuan ini menunjukkan perbedaan capaian yang besar pada konteks dua kelas yang diteliti, meskipun interpretasinya tetap perlu mempertimbangkan perbedaan kemampuan awal karena peserta didik tidak diacak secara individual.