This paper aims to contribute to recent literature exploring whether the accommodation strategy is beneficial for mainstream political parties. The main theoretical proposition of the paper is that the effectiveness of the accommodation strategy is conditional on where in the policy space a mainstream party shifts to. In addition, I distinguish between two different types of shift. The first is when the mainstream party shifts to a position that is more ideologically extreme than the niche party, or an ‘over shift.’ The second is when the mainstream party shifts to a position that is less ideologically extreme than the niche party, or an ‘under shift.’ To test my argument, I analyze 64 mainstream political parties in 15 European countries from 1981-2018. My results indicate that over shifting increases mainstream party vote share but has no effect on niche party vote share, and under shifting has no effect on either mainstream party vote share nor niche party vote share. My findings have implications for how mainstream parties should compete with their niche party rivals.