Rule 23(a)(1) requires impracticability of joinder rather than a specific number. Courts consider class size, geographic dispersion, the ability to identify members, and the size of individual claims.
Classes of forty or more are commonly found sufficient, though no threshold is fixed.
Alternative Names:
Numerosity Requirement, Rule 23(a)(1)
Why it Matters?
Numerosity is rarely contested successfully because the standard is impracticability rather than impossibility, and courts accept classes well under a hundred where members are dispersed or claims are small. The productive challenge is not to the number but to whether the plaintiff can establish class size at all, since a proposed class whose membership cannot be estimated fails on this element and on ascertainability together.
Frequently Confused with
Related terms
Frequently asked questions
Is there a minimum class size?
When is numerosity contestable?
