CA AB1866

Requires the State Department of Education to enhance the California Longitudinal Pupil Achievement Data System to include pupil attendance data, subject to available state, federal, or private funding.

Mandates the system generate periodic reports to local educational agencies showing rates of absence, chronic absenteeism, truancy, habitual truancy, and chronic truancy at district, school, and individual pupil levels for kindergarten through grade 12.

Defines "chronic absentee" as a pupil absent 10 percent or more of schooldays in a school year and "rates of absence" to include specific calculations of excused, unexcused, and suspended absences.

Allows local educational agencies to submit attendance data at any time during the year but requires minimum submission and certification at year-end or on dates determined by the department, with reports disaggregated by race/ethnicity, gender, disability status, English learner status, foster youth status, and free/reduced-price meal eligibility.

Establishes legislative intent that early warning systems using attendance and other predictors be used to support at-risk pupils through intervention and prevention rather than punitive measures, and provides for state reimbursement of any mandated local costs.