I examine the passage of alternative teacher certification policies in the states between 1975 and 2000 using event history analysis and supplementing the event history analysis with an ordinary least squares regression analysis of the strength of the alternative teacher certification policies. In order to test both teachers unions political strength external to state legislatures and teachers unions political strength internal to state legislatures, I use two variables to measure teachers union political strength. One variable measures the percentage of teachers in a state who work under union-negotiated contracts. The other variable measures the percentage of legislators in a state who list their non-legislative occupation as K-12 education. Control variables include teacher shortages, per pupil spending, legislative professionalism, divided government, democratic governor, percentage of minority students, change in percentage of minority students, an electoral threat index, and a time counter. Although the event history model results were inconclusive with respect to the teachers union political strength variables, the policy strength model results reveal that states with large percentages of teachers who work under union-negotiated contracts are more likely than other states to pass weak alternative teacher certification policies. This result supports the notion that teachers unions operate in the education policy-making arena.