This study evaluated the feasibility of the Knowledge, Language, and Inquiry (K.L.I.) intervention, designed to support Grades 3-5 multilingual students classified as English learners (ML-ELs) in building content knowledge, language skills, and reading comprehension through inquiry-based small-group instruction. Feasibility was examined across five dimensions--acceptability, practicality, integration, implementation fidelity, and effectiveness--using teacher interviews, ratings, lesson observations, and student and teacher learning outcome assessments. Findings suggest that the intervention was generally well-received by teachers, with structured lesson plans and resources facilitating implementation. Teachers demonstrated increased knowledge in reading instruction and the intervention following professional development, and students showed gains in vocabulary, text structure awareness, and topic-specific knowledge. However, time constraints during standardized testing periods limited consistent implementation. These findings inform the refinement of the K.L.I. intervention for broader application, emphasizing the need to address contextual challenges and conduct future evaluations to support its larger-scale implementation and improve ML-ELs' literacy outcomes. [This paper will be published in "The Journal of Educational Research."]