The growth of plant organs is driven by cell division and subsequent cell expansion. The transition from proliferation into expansion is critical for the final organ size and, consequently plant yield. Exit from proliferation and onset of expansion is accompanied by major metabolic reprogramming, and in leaves with the establishment of photosynthesis. To learn more about the molecular mechanisms underlying the developmental and metabolic transitions important for plant growth, we used untargeted proteomics and metabolomics analyses to profile young leaves of a model plant Arabidopsis thaliana representing proliferation, transition, and expansion stages. The third true leaves of the in vitro grown Arabidopsis seedlings were harvested daily from day 8 to day 13 after stratification (8 to 13 DAS). Days 8 and 9 correspond to proliferation, days 12 and 13 to expansion and days 10 and 11 to the transition. The dataset presented represents a unique resource comprising approximately 4000 proteins and 300 annotated small-molecular compounds measured across six consecutive days of leaf growth. These can now be mined for novel developmental and metabolic regulators of plant growth and can act as a blueprint for future studies aimed at better defining the interface of development and metabolism in any other species.