||The purpose of this case study was to understand how the implementation of a component from the Sheltered Instruction Observational Protocol (SIOP) model would be effective in an adult language classroom. More specifically, this study seeks to better understand how the component of comprehensible input could act as a motivational tool for adult language learners, especially in term of students' listening (receptive) and speaking (productive) skills. In addition, the ARCS model of motivation was incorporated in this study to see its effect on students' attention, relevance, confidence, and satisfaction levels in learning the language. Using an adult language classroom in a communication language development center, situated in an urban, diverse area in the Midwest as the project setting, data was collected through surveys, semi-structured interviews and observations over a three-month period. It was found that incorporating the comprehensible input components of speech appropriateness, clear explanation of tasks, and using a variety of teaching techniques positively impacted adult motivation to learn the language; successfully. The most significant outcome of this research is how the SIOP model has improved adult learners' ability to listen more effectively and speak confidently. Effective learning can be achieved successfully only when educators understand and are able to create techniques that work best for students and their needs. Therefore, implementing comprehensible input clearly showed that adult learners are more motivated in their classroom as they become more attentive in participating and more confident in voicing their opinions.