The Australian compulsory superannuation system contains nearly $AUD 3 trillion in funds, which is a substantial share of the personal wealth held by Australians. This means decisions made by superannuation trustees are important for everyone in Australia, both as beneficiaries and as participants in the Australian economy. The regulation of trustee decision-making, like the superannuation system as a whole, is founded on the equitable principles of trust law, but with an extensive overlay of legislative and regulatory intervention. Examining the regulation of decision-making in this context provides important insights into foundational trust law principles as well as a major component of wealth management in Australia.