Although open science has become a popular tool to combat the replication crisis, it is unclear whether the uptake of open science practices has been consistent across the field of psychology. In this study, we were particularly interested in whether claims that developmental psychology lags behind other subfields in adopting open science practices were valid. To test this, we determined whether data and material sharing differed as a function of psychological subfield at the distinguished journal, Psychological Science. The results showed that open data and open materials scores increased from 2014–2015 to 2019–2020. Of note, articles published in the field of developmental psychology generated lower open data and open materials scores than articles published in cognition; however, scores were similar to articles published in social psychology. Across Psychological Science articles, shared data and materials were seldom accompanied by documentation that is likely to make shared research objects useful. These findings are discussed in the context of the unique challenges faces by developmental psychologists and how journals can more effectively encourage authors to practice open science across psychology.