Pour water in a large pot. Ensure the water will not touch the bottom of the steamer basket, even when boiling, if possible. Bring water to a boil over high heat.
While water is coming to a boil, place the shrimp in your steamer basket. Sprinkle with Old Bay Seasoning and toss to coat as evenly as possible.
Carefully place the steamer basket in the pot and cover. Reduce heat to medium, or enough to maintain a gentle boil.
Steam for 4 to 6 minutes (will depend upon the size of your shrimp). Remove lid after 2 to 3 minutes and toss shrimp (using tongs). Cover with lid and continue to steam until shrimp have just turned pink and are opaque.
Sprinkle with parsley when serving, if desired. Serve warm or chilled with lemon wedges, melted butter and/or cocktail sauce, if desired.