Short answer. Very specific. Section 5 of Rule 8 requires that circumstances constituting fraud or mistake be stated with particularity — a general accusation is not enough. By contrast, a person's malice, intent, knowledge, or other mental condition may be averred generally.
What the law says
In all averments of fraud or mistake, the circumstances constituting fraud or mistake must be stated with particularity. Malice, intent, knowledge or other condition of the mind of a person may be averred generally.
Rule 8, Section 5 — Fraud, mistake, condition of the mind. Read the full provision →
Particularity is required for fraud and mistake
Section 5 sets a heightened pleading standard for two specific categories: in all averments of fraud or mistake, the circumstances constituting fraud or mistake must be stated with particularity. This means a complaint alleging fraud cannot simply assert, in general terms, that the defendant defrauded the plaintiff — it needs to lay out the specific circumstances: what representations were made, when, by whom, and how they were false or misleading, so that a bare conclusory label of 'fraud' is not enough on its own. This particularity requirement binds whichever party is averring fraud or mistake, whether that is a plaintiff alleging it in a complaint or a defendant raising it as an affirmative defense; the heightened standard does not turn on which side of the case is making the allegation.
Why fraud gets special treatment
Fraud and mistake carry serious implications and can be easy to allege but hard to prove, which is presumably why the Rules require the specifics up front rather than allowing a bare, conclusory accusation to put a defendant on the defensive. Particularity in the pleading gives the defendant fair notice of exactly what conduct they need to answer for, rather than a vague charge they cannot meaningfully respond to, and it discourages plaintiffs from throwing in a fraud claim simply to gain leverage. Courts have historically been wary of fraud claims tacked on as an afterthought precisely because the label carries so much weight without the specifics to back it up.
The contrast: mental states can be pleaded generally
Section 5's second sentence draws a sharp contrast: malice, intent, knowledge or other condition of the mind of a person may be averred generally. Unlike the specific circumstances of fraud itself, the underlying mental state — what the person knew, intended, or was motivated by — does not need to be pleaded with the same particularity, since a party ordinarily cannot know with precision what was in someone else's mind and can only allege it in general terms, leaving the details to be proven later through circumstantial evidence at trial. A pleading that fails to state the circumstances of fraud with particularity does not automatically fail on the mental-state element too; the two sentences of Section 5 set independent standards, so a defect in pleading the surrounding circumstances does not by itself excuse the pleader from the general averment of malice, intent, or knowledge that the same claim may also require.