This guide covers relocation and interstate custody from the jurisdictional threshold through enforcement of an order across state lines. Part 1 sets out the jurisdictional architecture, which decides more cases than the merits do. Parts 2 and 3 cover initial jurisdiction, continuing exclusive jurisdiction, emergency jurisdiction, registration, and inconvenient forum, with the errors that recur at each step. Part 4 covers relocation notice statutes and the content that makes a notice letter an asset rather than a liability. Parts 5 and 6 cover burden allocation and the factors courts weigh regardless of who carries the burden. Part 7 covers the long-distance parenting plan in drafting detail. Part 8 covers evidence and the custody evaluation. Parts 9 through 12 cover military parents, domestic violence, international relocation under the Hague framework, and enforcement, modification, and the errors that recur on both sides.