When you're in the mood for cuddles, you love it when dog chooses to sit on your lap. At other times, however, it's simply not convenient. Reasons for this behavior range from his personal comfort to canine strategy. Since he won't tell you outright, look to his other behavior for context clues that help explain why he'd rather sit on you than on the floor or sofa.
NOTE: "Dominance Theory" is a widely debated topic among dog behaviorists, but we at Cuteness like to give voice to writers on both sides of the debate. For an opposing view, please see our article Social Hierarchy Among Dogs.
Your dog may simply be happy to see you after a long day without you. For many dogs, sitting beside you -- or on top of you -- is a nice way to spend time together. If you reward your dog's behavior with pets and cuddles, he may have learned that this behavior gets him lots of good affection.
Behaviors like jumping up on your lap or pawing at your legs to be picked up can be signs of dominance. If your dog tries to claim a certain chair as his, snapping when you try to move him over or push him off, or growls if you disturb his beauty rest, playtime or snack, he may be asserting dominance over you in this situation.
For some pups, lap sitting is part of a scent bombing campaign. As your dog sits on your lap or even your foot, he rubs some of his scent on you. You may only notice that you've got fur on your nice black shirt, but other dogs will pick up on his scent. Part protective, part dominant, this helps your pet claim you as his owner even when he can't go with you.
Sometimes lap sitting is about your behavior and not your pet's. Dogs can tell when you're sick or sad and may offer affection via lap sit to cheer you up. For some dogs, there's nothing more to this behavior other than a desire to have the most comfortable spot in the house -- your lap! If your pet falls asleep on your lap, he may be trying to recreate the pack sleeping arrangement: Dogs sleep all over one another, and lying on your lap resembles that.
ASPCA: Is Your Dog Dominant?
VetStreet: 14 Common Dog Behavior Myths Decoded
Woman's Day: 9 Things Your Dog Wants to Tell You
Psychology Today: Canine Empathy: Your Dog Really Does Care If You Are Unhappy