Neuroblastoma is a pediatric tumor that originates from cells of the adrenergic lineage. Here we investigated the balance between differentiation and dedifferentiation in relation to tumor-engraftment potential in preclinical mouse models. We analyzed intratumoral heterogeneity through comparison of marker expression of normal adrenergic development versus tumor marker expression, which showed the presence of sympathoadrenal as well as mesenchymal subtypes of neuroblastoma cells. Subsequently, we evaluated long-term outgrowth capacity of these two (FACS-sorted) cell populations, which showed that adrenergic cells have a stronger long-term clonogenic potential. Engraftment of these sorted populations into mice revealed the occurrence of heterogeneous populations. Modelling of the interconversion rate indicated that cell fate transitions from the adrenergic to mesenchymal state were obtained gradually and stochastically as the tumors grew in mice. We found that adrenergic cells have an increased tumorigenic potential in mice without signs of beneficial cross talk between the two lineage populations. These findings indicate that neuroblastoma contains two rivalling differentiation states that exhibit differences in long term clonal/tumorigenic potential. We expect these states to be relevant for therapy resistance as a result of intratumoral heterogeneity.