Although widely used across psychology, economics, and philosophy, the concept ofeffort is rarely ever defined. This article argues that the time is ripe to look for anexplicit general definition of effort, makes some proposals about how to arrive at thisdefinition, and suggests that a force-based approach is the most promising. Section 1presents an interdisciplinary overview of some chief research axes on effort, and arguesthat few, if any, general definitions have been proposed so far. Section 2 argues thatsuch a definition is (...) now needed and proposes a basic methodology to arrive at it, whosefirst step is to make explicit the various tacit assumptions about effort made acrosssciences and ordinary thinking. Section 3 unearths 4 different conceptions of effortfrom research on effort so far:primitive-feelings accounts,comparator-based accounts,resource-based accountsandforce-based accounts. It is then argued that the first 2kinds of accounts, although interesting in their own right, are not strictly speaking abouteffort. Section 4 considers the 2 most promising general approaches to efforts: re-source-based and force-based accounts. It argues that these accounts are not only compatible but actually extensionally equivalent. This notwithstanding, it explains why force-based accounts should be regarded as more fundamental than resource-basedaccounts -/- . (shrink)