A project-based engineering education unit was implemented in a primary school in Cambodia. An effectiveness study was conducted to investigate students' attitudes and expectations of engineering as a profession and students' self-perceived 21st century skills. The findings revealed that prior to the curriculum implementation both male and female students had positive attitudes toward engineering, positive beliefs toward the role of engineering in their lives, and highly favorable perceptions about their perceived 21st century skills. Results indicated no significant increase in overall students' attitudes and expectations of engineering, or self-perceived 21st century skills. Yet, students who had an average mean score of less positive feelings on the pre-assessment showed significant increases in their attitudes and expectations toward engineering, as well as their self-perceived 21st century skills. These findings indicate that students at the primary level in Cambodia are either already enthusiastic about engineering or are significantly more so once exposed to an engineering curriculum. The importance of incorporating engineering principles into the Cambodian curriculum are discussed.