The present study provides a substantive-methodological perspective on students’ willingness
to engage in problem solving, a motivational determinant of 21st century skills. In
particular, we study the usefulness of different models to describe (a) the structure of students’
openness and perseverance as indicators of their willingness to engage in problem
solving; (b) the measurement invariance and mean differences across three countries; and
(c) the relation to students’ performance in creative problem solving. Using the PISA 2012
data sets of Australia, Norway, and Singapore, we apply multi-group structural equation
modeling to address our objectives. The results show that a correlated-traits–correlated-
(methods-1) model represents the structure of openness and perseverance, and that scalar
invariance is met. Regarding the differences in the levels of openness and perseverance
across countries, we find the highest levels of perseverance in Singapore and the lowest
levels in Norway. The inverse effects are present for students’ openness. Moreover, we find
only small cross-country differences in the relations to problem solving performance. Our
findings shed light on the measurement and modeling of openness and perseverance as
motivational aspects of 21st century skills.