Reading is a fundamental skill in our modern society; being able to read with comprehension and fluency is an important skill in all core academic subjects. Reading teachers are charged with the task to analyze student data in order to drive their instructional decisions. Informal Reading Inventories (IRIs) are one type of an informal reading assessment that teachers can use in the classroom to learn about student reading behaviors and drive instruction. Informal Reading Inventories assess fluency and comprehension. Research suggests that fluency and comprehension have a reciprocal relationship; meaning, if you improve one skill, you improve the other skill simultaneously (DeVries, 2011). This study explored how pre-service teachers, college students in an education program, and in-service teachers, veteran teachers, analyzed data from various IRIs. This study also explored how three separate IRIs, the Qualitative Reading Inventory (QRI), the Basic Reading Inventory (BRI), and the Analytical Reading Inventory (ARI), compared to one another. There were four participants in this study: two undergraduate students in an elementary education program reading class and two veteran classroom teachers. This study found that the grade level readability of the passages are inconsistent with the reading level they claim to be. An inconsistency like this is something to note as many teachers only use these resources on which they were trained during their college education. This study also found that the length of the IRI passages had an effect on the student’s words correct per minute (WCPM); the longer the passage, the lower the WCPM. This is probably due to the fact that students need more time to process a passage for the sake of comprehension.