For much of the twentieth century, economic historians treated the craft guilds of premodern Europe as a byword for institutional sclerosis. In this account, guilds were essentially cartels: associations of masters that restricted entry, fixed prices, suppressed labor-saving techniques, and diverted resources from productive activity toward the defense of monopoly privilege. The apparent acceleration of economic growth in regions where guild authority waned - England after the seventeenth century is the favored example - was read as confirmation. Where guilds persisted, the story went, innovation stalled; where they crumbled, industry flourished. A revisionist literature has complicated this indictment without wholly overturning it. Its central claim is that the older view mistook the guilds' rhetoric for their function. Guild ordinances did proclaim monopolies and did inveigh against interlopers, but enforcement was frequently lax, entry was more porous than the statutes imply, and many ordinances went unobserved for decades. More importantly, revisionists argue, guilds addressed genuine economic problems that unregulated markets handled poorly. In trades where buyers could not readily judge quality before purchase - metalwork, textiles, pharmaceuticals - a guild's collective brand assured consumers that goods met a standard, and the guild's power to inspect and to expel offenders gave the assurance teeth. Guilds also structured apprenticeship, transmitting tacit skills that no manual could codify and that individual masters, fearing their trainees would defect, might otherwise underinvest in teaching. Yet the revisionist case has limits that its more enthusiastic proponents sometimes elide. That an institution solved a problem does not establish that it solved the problem efficiently, still less that no cheaper solution was available. Quality certification might have been supplied by reputation, by merchant intermediaries, or by the state; apprenticeship contracts might have been enforced by ordinary courts. To show that guilds performed a useful function, one must also show that the alternatives were worse - a comparison the revisionist literature more often assumes than demonstrates. Moreover, the same inspection powers that policed quality could police competition, and the historical record rarely lets us cleanly separate the two. A guild expelling a master for shoddy work and a guild expelling a master for underselling his fellows leave nearly identical documentary traces. The most defensible reading, then, is neither the cartel thesis nor its revisionist mirror image but a recognition that guilds were multivalent. They were simultaneously instruments of exclusion and instruments of coordination, and the balance between these functions varied by trade, city, and century in ways that resist any single verdict. What the debate has usefully dislodged is the reflexive assumption that a durable institution must be either efficient - because it survived - or parasitic - because it constrained. Survival, the revisionists rightly insist, is weak evidence of social benefit, since an institution that enriches its members can persist by capturing the authorities who might otherwise curb it. But that same insight cuts against the revisionists too: the persistence of guilds no more proves their utility than it proved, for an earlier generation, their harm.