With the emphasis on building twenty-first-century skills in learners, English language teachers are challenged to find activities that will build English language proficiency while promoting higher-order thinking in the target language. One reason is that an individual learner's zone of proximal development (ZPD) for language proficiency and for critical thinking may be different. ZPD--the difference between the learner's ability to solve problems independently in relationship to his or her ability to solve problems with guidance (Vygotsky 1978)--is an important concept to consider when developing twenty-first-century skills. Inquiry-based learning takes ZPD into consideration by using scaffolding to guide the learner through the process of posing questions, thinking critically about issues, and solving problems (Chu et al. 2017). One method to incorporate inquiry-based learning into a language classroom--and help students process their experience, develop language proficiency, and build twenty-first-century skills--is through inquiry notebooks. The transition from high school to college can be difficult socially and academically, and many learners do not have a formal outlet to share their experiences. This led the author to use inquiry notebooks with first-year university students to get them to think critically about their college experience, both in and out of the classroom. This article will explain the rationale and describe the procedures to implement inquiry notebooks as an instruction tool to put twenty-first-century skills in reach for English learners.