Prior studies have established an extensive literature on accounting comparability, largely with the focus on its economic consequences. However, the current literature is characterised by at least two limitations. First, the prior studies on earnings comparability document evidence exclusively for GAAP earnings despite the fact that non-GAAP earnings are widely used by market participants. Second, while research has examined the economic consequences of comparability, limited attention has been given to the underlying mechanism that produces more comparable (or incomparable) earnings. My thesis, composed of two related studies, aims to contribute to these two gaps. Chapter 4 seeks to fill the first gap by bridging the literatures on accounting comparability and non-GAAP earnings. Specifically, I find that non-GAAP adjustments are associated with significant comparability benefits. Chapter 5 aims to close the second gap regarding the underlying mechanism that produces comparable (or incomparable) earnings. The main finding suggests that earnings comparability is partially driven by firms’ accrual components. These findings combined contribute to the literature by furthering our understanding of the underlying determining factors for earnings comparability.