The Pennsylvania State University seeks to develop and evaluate the effectiveness of an early numeracy skill promotion program, NumberFun, designed for use with children in Head Start programs. Specifically, the program will examine whether implementation of the NumberFun program is feasible in Head Start classrooms and whether it is effective in fostering early numeracy skills in Head Start children. Participants will include 240 Head Start children from eight classrooms. Classrooms will be matched on teacher and classroom characteristics and then one classroom from each pair will be randomly assigned to the NumberFun or control conditions. Children's early mathematics skills will be measured using the Test of Early Mathematics Ability, 3rd Edition and EARLI Numeracy Probes. In addition, implementation fidelity will be measured at several points throughout the year using the Implementation Fidelity Checklist and the Numeracy Instruction Self-report. Researchers anticipate that implementation of the NumberFun program will be feasible in Head Start classrooms and effective in promoting early numeracy skills in Head Start children. Results from this are expected to benefit curriculum, instruction, and assessment for Head Start centers and fill in the knowledge gap concerning numeracy development and instruction.