This paper examines late career mobility and retirement decisions for a cohort of mid-career Missouri public school teachers. The rate of accrual of traditional defined benefit pension systems is highly nonlinear and back-loaded with most of the gain occurring in the final years prior to retirement. Also, these pension systems have rules that introduce kinks or discontinuities in the rate of accrual after 30 years. This paper explores the effect of these pension rules on retirement patterns. Missouri permits teachers to continue teaching part-time while collecting benefits. Teachers can also retire from one pension system and begin teaching in another. The paper examines both types of behavior.