This paper claims that a wide variety of grammatical coding asymmetries can be explained as adaptations to the language users’ needs, in terms of frequency of use, predictability and coding efficiency. I claim that all grammatical oppositions involving a minimal meaning difference and a significant frequency difference are reflected in a universal coding asymmetry, i.e. a cross-linguistic pattern in which the less frequent member of the opposition gets special coding, unless the coding is uniformly explicit or uniformly zero. I give 25 examples of pairs of construction types, from a substantial range of grammatical domains. For some of them, the existing evidence from the world’s languages and from corpus counts is already strong, while for others, I know of no counterevidence and I make readily testable claims. I also discuss how the functional-adaptive forces operate in language change, and I discuss a number of possible alternative explanations.