As policy-makers contemplate expanding preschool opportunities for low-income children, one possibility is to fund two, rather than one year of Head Start for children at ages 3 and 4. Another option is to offer one year of Head Start followed by one year of pre-k. We ask which of these options is more effective. We use data from the Oklahoma pre-k study to examine these two "pathways" into kindergarten using regression discontinuity to estimate the effects of each age-4 program, and propensity score weighting to address selection. We find that children attending Head Start at age 3 develop stronger pre-reading skills in a high quality pre-kindergarten at age 4 compared with attending Head Start at age 4. Pre-k and Head Start were not differentially linked to improvements in children's pre-writing skills or pre-math skills. This suggests that some impacts of early learning programs may be related to the sequencing of learning experiences to more academic programming. [This paper was published in "Educational Evaluation and Policy Analysis" v38 n1 p88-112 Mar 2016 (EJ1089933).]