OBJECTIVES: To assess formulary decisions for selected newly approved drugs by Part D plans. METHODS: This retrospective cohort study identified formulary placement and restrictions for 34 drugs in 8 therapeutic classes (antihyperglycemics, anticoagulants, antiplatelets, MS agents, DMARDS, COPD drugs, antiepileptics, and antipsychotics) in 863 Part D plans with continuous CMS contracts between 2009 and 2014. Multivariable models estimated the impact of drug characteristics and Part D plan characteristics on probability of drug adoption; then, for adopters, evaluated factors associated with months to adoption, tier assignment, and application of prior authorization (PA) and step therapy (ST). RESULTS: First Part D formulary placements varied from 2 to 14 months post-FDA approval. On average, 58.5% of plans placed each drug within 6 months, and 65.9% within one year of National Drug Code assignment date. The most rapid adoption was for antipsychotics and antiepileptics. The slowest was for COPD drugs. Anticoagulants and antiplatelets were typically assigned to tier 3 with few restrictions, whereas MS agents and DMARDS were assigned to tier 5 with 90% or more subject to PA. ST was uncommon except for antihyperglycemic agents. In adjusted analyses, enhanced benefit plans and those with higher Star ratings had higher odds of formulary placement (1.38 and 1.36, p<0.01) whereas being a benchmark plan lowered odds of placement (0.78, p<0.01). Overall, MAPDs had higher placement rates due to enhanced plan offerings and higher Star ratings. CONCLUSIONS: There is significant heterogeneity in formulary placement and restrictions on new drug introductions in the Part D marketplace.