The purpose of this action research project was to compare two types of ability grouping and if one type had more of an impact than the other in a primary classroom. In this study, one type of ability grouping, known as within class ability grouping was implemented in one second grade classroom in 2017-2018. Another type of ability grouping was implemented the next year where all three of second grade classrooms were grouped according to ability, which is considered to be within grade ability grouping. Students were assessed with the AddVantage+MR (AVMR) assessment to determine placement. Then they were placed into groups and worked with other students to work on math skills that they all struggled with. The researcher’s hope was to determine if there was a greater impact on one type of ability grouping than the other.