The reliability of population dynamics and stock assessment models hinges on accurate life-history information. Mark-recapture studies represent a commonly used technique to investigate crustacean growth, mortality, and migrations. We evaluated tagging by coded microwire tags for the American lobster, Homarus americanus H. Milne Edwards, 1837, in a controlled study to determine tag retention and any influence on growth increment, intermolt duration, or survival. Microwire tags were injected into the propodus of the second right walking leg and two size classes (12–19.6 and 19.7–30 mm carapace length [CL]) were tested by two individual taggers. Overall tag retention was 96%. Tag retention after first ecdysis was 95% for the 12–19.6 mm CL and 92.5% for the 19.7–30 mm CL size class. There was no significant difference in tag retention between taggers, growth between tagged and untagged lobsters, or intermolt duration between tagged and untagged lobsters (P > 0.05 for all tests). Tag-induced mortality did not occur. These results support the further use of coded microwire tags to explore life-history variables for juvenile lobsters in the wild.