Below are links to the individual state rules/statutes on class actions. Most included rules are part of the respective state rules of civil procedure.
ALABAMA: . (Article 33, at bottom of page)
ALASKA: .
ARIZONA: .
ARKANSAS: .
CALIFORNIA: . (Division V, toward bottom of page)
COLORADO: . (Westlaw)
CONNECTICUT: . (Westlaw)
DISTRICT OF COLUMBIA: . (PDF, Page 47)
DELAWARE: . (PDF, Page 45)
FLORIDA: .
GEORGIA: .
HAWAII: .
IDAHO: .
ILLINOIS: .
INDIANA: .
IOWA: . (PDF, Page 39)
KANSAS: .
KENTUCKY: .
LOUISIANA: .
MAINE: .
MARYLAND: . (Westlaw)
MASSACHUSETTS: .
MICHIGAN: . (PDF, Rule 3.501 is on page 79)
MINNESOTA: . (Omitted)
MISSISSIPPI: .
MISSOURI: .
MONTANA: .
NEBRASKA: .
NEVADA: .
NEW HAMPSHIRE: .
NEW JERSEY: .
NEW MEXICO: . (New Mexico Statutes and Court Rules > Contents of Judicial Volumes > Rules of Civil Procedure for the District Courts > 1.023)
NEW YORK: .
NORTH CAROLINA: .
NORTH DAKOTA: . (Westlaw)
OHIO: .
OKLAHOMA: . (RTF, Page 303)
OREGON: . ("Find" function, "rule 23")
PENNSYLVANIA: .
RHODE ISLAND:
SOUTH CAROLINA: .
SOUTH DAKOTA: . ("Find" function, "15-6-23")
TENNESSEE: . ("Find" function, "Rule 23")
TEXAS: . (PDF)
UTAH: .
VERMONT: . (Vermont Court Rules > Rules of Civil Procedure > IV. Parties > Rule 23)