The Government of Tanzania is in the process of implementing a policy of one year of free and compulsory pre-primary education for all children. The policy pronouncement was made within the context of limited resources for education and unclear implementation guidelines. Nonetheless, the declaration of fee-free and compulsory pre-primary led to an immediate increase in enrolment of 46% in the year after the policy was established. While access has improved, quality has not. A recent study of school readiness of children starting Standard 1 in Mainland Tanzania (78% of whom completed pre-school) found no difference between those who attended pre-primary school and those who did not (RTI International, 2017). The study also found weaknesses in the quality of early learning environments, such as high pupil-teacher ratios, poor pedagogy, and lack of high-quality teaching and learning materials. The key challenge facing the Government of Tanzania is how to develop an early learning system that can produce learning, not just broaden access, and to do so in a manner that is sustainable. Earlier experiences with the drive for universal primary education have shown that it is possible (and perhaps easier) to improve access to school without producing any learning. The current study uses a scale and sustainability framework proposed by Crouch and DeStefano (2017) to examine the extent to which the pre-primary (early learning) education system in mainland Tanzania is set up to provide quality pre-primary at scale and sustainably. They identified a core set of functions that education systems should be able to perform to produce learning: (1) set and communicate learning expectations; (2) monitor against expectations; and (3) provide minimum inputs to all schools, and targeted support to struggling schools and classrooms. We interviewed various actors at the national, district and school levels including government officials from the ministries responsible for education and local government; head teachers; teachers; parents of pre-primary aged children; and lecturers and administrators from teacher training colleges. In addition, we reviewed policies, plans, and strategies related to education and development. We found that the early learning system is still developing its capacity to perform the identified core functions. There are some learning goals outlined in a new curriculum, but most of the goals expressed in plans and policies relate to access, not learning, and are not known throughout the system. Monitoring against learning is weak as officials responsible for monitoring schools are unable to do so on a regular basis, and even when they do go, their observation protocols are not linked to learning or curricula expectations. Accountability mechanisms are weak as there is not enough data within the system to track performance against learning expectations. Finally, the Government of Tanzania struggles with providing basic instructional inputs – teachers, teaching and learning materials, continued professional development – to the pre-primary school system. This study and its findings are important because they point to priority areas for system reform for the Government of Tanzania and other countries facing the challenge of producing learning at scale sustainably.