<![CDATA[Abstract: This study aims to analyze the influence of peer group and social media use on the consumptive behavior of students at SMAN 1 Batang Kuis. This research uses a quantitative method with an ex post facto approach. The population consisted of 344 students, with a sample of 185 students taken using proportional random sampling. Data collection was carried out through a questionnaire instrument that has been tested for validity using Aiken's V formula and reliability using Cronbach's Alpha. Data analysis techniques include descriptive analysis, classical assumption tests (normality, linearity, multicollinearity, heteroscedasticity), multiple linear regression analysis, and hypothesis testing (t-test and F-test). The results showed that: (1) the peer group environment has a positive and significant effect on consumptive behavior; (2) the use of social media has a positive and significant effect on consumptive behavior; (3) the peer group environment and the use of social media simultaneously have a positive and significant effect on consumptive behavior. The coefficient of determination (R²) of 0.302 indicates that both independent variables contribute 30.2% to consumptive behavior, while the remaining 69.8% is influenced by other variables. Keywords: Peer Group; Social Media Use; Consumptive Behavior Abstrak: Penelitian ini bertujuan untuk menganalisis pengaruh lingkungan teman sebaya (peer group) dan penggunaan media sosial terhadap perilaku konsumtif siswa SMAN 1 Batang Kuis. Penelitian ini menggunakan metode kuantitatif dengan pendekatan ex post facto. Populasi berjumlah 344 siswa, dengan sampel sebanyak 185 siswa yang diambil menggunakan teknik proportional random sampling. Pengumpulan data dilakukan melalui instrumen angket yang telah diuji validitasnya menggunakan rumus Aiken's V dan reliabilitas menggunakan Cronbach's Alpha. Teknik analisis data meliputi analisis deskriptif, uji asumsi klasik (normalitas, linearitas, multikolinearitas, heteroskedastisitas), analisis regresi linear berganda, dan uji hipotesis (uji t dan uji F). Hasil penelitian menunjukkan bahwa: (1) lingkungan teman sebaya berpengaruh positif dan signifikan terhadap perilaku konsumtif; (2) penggunaan media sosial berpengaruh positif dan signifikan terhadap perilaku konsumtif; (3) lingkungan teman sebaya dan penggunaan media sosial secara simultan berpengaruh positif dan signifikan terhadap perilaku konsumtif. Nilai koefisien determinasi (R²) sebesar 0,302 mengindikasikan bahwa kedua variabel bebas memberikan kontribusi sebesar 30,2% terhadap perilaku konsumtif, sedangkan sisanya 69,8% dipengaruhi oleh variabel lain. Kata kunci: Lingkungan Teman Sebaya; Penggunaan Media Sosial; Perilaku Konsumtif]]>
