Abstract Humane dog and cat population management has relied on Trap, Neuter, Release (TNR) projects in an attempt to control or reduce free-roaming populations and improve the welfare of dogs and cats. It has been recognised that the root cause of dog and cat population and welfare issues is people and their attitudes and behaviours towards dogs and cats – whether this is through lack of responsible ownership leading to loss or abandonment, or programs that focus on single tools such as sterilisation. Failing to recognise the interdependency that exists between individual and community responsibility means that projects that rely solely on the actions of an individual or a small group, and do not involve the wider community, risk limiting their impact and sustainability. Typically, sterilisation projects regularly fail to address this issue. The concept of human behaviour change is beginning to be used in dog population management programs but is still largely unused and untested in cat population management programs. In 2013, a 4-year project in Praia de Faro, Portugal, started to explore how communities respond to a local program using community engagement tools to measure and evaluate changes in attitudes and behaviours towards owned and un-owned dogs and cats. The research question is: ‘does community involvement and participation in a project increase its chances of success in relation to improved welfare for animals?’ Results suggest improved dog and cat welfare, positive changes in attitudes and behaviours of the community, and increased community involvement.