Scale Terraform across real AWS accounts with clear guardrails, fast promotion, and production grade state. Many teams stall when a single AWS account, ad hoc repos, and long lived keys collide with audit needs and on call reality. This guide shows a proven multi account structure with Organizations and Terragrunt so you ship changes safely, control cost, and pass reviews without ceremony. You get a practical path, from landing zone and repository design to CI, approvals, and runbooks. Every pattern favors readability, short lived credentials, and code you can promote by version bump, not by copy paste. Structure Organizations with OUs for development, staging, production, security tooling, and log archive - Design accounts and backends that isolate state by environment, no CLI workspaces - Apply Service Control Policies, region allow lists, root user protections, and pass role limits - Enforce Tag Policies for cost allocation and compliance with required keys and allowed values - Choose between Control Tower, AFT, and Landing Zone Accelerator, know when to roll your own - Build a catalog and a live repo, pin module versions with release tags, and promote cleanly - Use terragrunt stack files to compose units, wire outputs only, and speed plan time with mocks - Operate state with S3 lockfiles, KMS encryption, bucket policies, versioning, and lifecycle rules - Migrate safely from DynamoDB state locks without downtime - Adopt IAM Identity Center for engineers and OIDC for CI, set role trust by repo and branch - Orchestrate across stacks, read the dependency DAG, queue and parallelize without surprises - Tune performance with provider plugin cache, adaptive retries, and controlled parallelism - Run PR based plans with Atlantis or pure Actions, require reviewers and protected environments - Rollback and fix forward under pressure, handle partial applies and drift with discipline - Set budgets, anomaly detection, and cost categories per environment - Protect secrets and sensitive variables, set sane provider defaults with generate blocks - Audit state access with CloudTrail data events, prefer data events over S3 access logs - Test with Terratest, write smoke tests and teardown routines that fit real accounts - Apply incident playbooks, state recovery, SLOs, break glass access, and post incident reviews - Follow a complete capstone, repository skeleton to CI with OIDC, approvals, and an ops runbook This is a code heavy guide with labeled HCL, JSON, YAML, and Bash examples that assemble into a working multi account platform you can adapt to your team. Get the playbook, reduce risk, and move faster, grab your copy today.