Researchers have used the Narver and Slater's construct (1990), hereafter (N&S), to operationalise market orientation (MO). The assumption is that the construct is universally equivalent across cultures, countries and research contexts. We develop a way of testing the invariance of N&S operationalisations as an example of how researchers can establish measure invariance across different cultures, countries or languages. In this particular study we test the N&S operationalisation across Australian and UK samples. The results suggest that the conceptualisation of MO is similar in the two countries at a weak factorial invariance level. Thereafter the operationalisation is different ie intercepts are significantly different and item reliabilities are also different. These results suggest that because measure equivalence is not strong, contextualisation of findings is necessary since generalisability may be limited. The significance of this research is in alerting researchers to the assumptions, rarely tested, that underlay comparisons across qualitatively distinct populations. We suggest researchers test these assumptions before substantive tests of theories are undertaken.