The development of digital technology provides opportunities, however Social Studies instruction in schools is still dominated by conventional teaching methods and learning media that are less capable of fostering students' critical thinking skills. This study aimed to develop the SocialMind application as a valid, practical, and effective learning medium to improve students' critical thinking skills. The research employed a Research and Development (R&D) approach using the ADDIE model consisting of analysis, design, development, implementation, and evaluation stages. The participants involved two material experts, two media experts, three Social Studies teachers, and 30 eighth-grade students of SMP Negeri 2 Waru. Data were collected through observation, interviews, documentation, questionnaires, and tests. Data analysis used Aiken's V coefficient, normality test, paired sample t-test, and N-Gain analysis. The results revealed that the SocialMind application obtained a media validity score of 0.772 and a material validity score of 0.738, indicating that the product was valid. The practicality level based on teachers' assessments reached 94.29%, categorized as highly practical. Furthermore, the paired sample t-test showed a significance value of 0.000 (p < 0.05), while the average N-Gain score was 0.6056, categorized as moderate. These findings indicate that the SocialMind is valid, practical, and effective in improving students' critical thinking skills in Social Studies learning.