By what age does the critical socialization window typically close for Labrador Retriever puppies?

Around 16 weeks.

The period designated as the critical socialization window for Labrador Retriever puppies is quite brief, generally concluding around sixteen weeks of age. Capitalizing on this specific timeframe is considered non-negotiable for ensuring the development of a stable adult temperament, even for a breed genetically inclined toward friendliness. During these formative months, puppies establish their baseline understanding of normalcy and safety. Introducing them calmly to a wide variety of stimuli—such as different surfaces like concrete or grass, various gentle sounds like traffic, and different types of people—during this impressionable stage is crucial. A failure to invest heavily in controlled, positive exposures during these first four months can lead to unwanted traits, like nervousness in public or excessive jumping, even in genetically sound puppies.