A number of scholars have raised concerns that many social marketers fail to consider the cost of their programmes and its related savings. One solution is to use the social return on investment (SROI) framework, which is rooted in the theory of change. To demonstrate its possibilities, a single case study, focusing on a small social enterprise based in the north of England, was used. They apply social marketing principles to influence positive behaviour changes in people living with learning difficulties. The study was limited to their Teens-n-Twenties programme, which was designed to support individuals between the ages of 14 to 25 become more independent. The results demonstrate that the programme had an SROI valued somewhere between 2.36:1 and 3.88:1 (i.e., for every £ invested, a value of between £2.36 and £3.88 was delivered in social worth). This evaluation was used as evidence of the programme’s effectiveness in a continuing funding bid, and the organisation was awarded just under £500K from the UK’s Big Lottery Fund. The study contributes to the knowledge and practice of social marketing by presenting a possible solution to the domain’s concerns on how social marketing can be evaluated.