This guide is a working reference to child support for parents, advocates, and family law practitioners. It sets out the guideline models and the statutory framework that requires them, then treats the inputs that actually decide cases: the broad definition of income, the self-employment analysis that turns on bank records rather than tax returns, imputed income where a parent is voluntarily unemployed or underemployed, and the parenting time thresholds that move numbers sharply. Establishment chapters cover the state program route and the private action, the elements every order should contain, and the retroactive support available to the filing date. Modification receives extended treatment because retroactivity generally begins at filing, making delay the most expensive error in the field. Enforcement chapters cover income withholding and its higher garnishment ceiling, tax intercepts, liens, license suspension, the locator service, contempt with its ability-to-pay requirement, and the non-dischargeability of support in bankruptcy. Interstate chapters address controlling orders and continuing exclusive jurisdiction.