Domain-Driven Design (DDD) is an approach to software development that emphasises high-fidelity modelling of the problem domain, and which uses a software implementation of the domain model as a foundation for system design. This approach helps organize and minimize the essential complexity of your software. DDD has been used with success within the traditional enterprise programming ecosystems of Java and .NET, but has seen only limited adoption in the Python community. In this talk we introduce Python programmers to the core tactical patterns of DDD and show how they can be realised in idiomatic Python, freeing the most valuable parts of your system – the domain model – from onerous dependencies on particular databases or application frameworks. In this talk we share what we've learned from applying DDD in Python to large projects.