The Mom Test

Asking about people's past behavior so even your mom can't lie to you about your idea.

Also known as: mom test, the mom test, Rob Fitzpatrick

The Mom Test (from Rob Fitzpatrick’s book of the same name) is a rule for customer conversations: ask about past behavior, never about your idea — so that even your mom, who loves you and your startup, cannot accidentally lie to you. Compliments and predictions are worthless; stories about what someone actually did, paid and tried are gold.

bad (lies welcome):   "Do you think this is a good idea?" → "Sounds great, honey!"
good (lies blocked):  "Tell me about the last time you tried to solve this. What did you do?"

Three rules cover most of it. Talk about their life, not your idea. Ask for specifics from the past instead of opinions about the future. Bad news is the only news — a conversation that kills your idea in twenty minutes saved you six months.

The classic mistakes:

Fishing for compliments. “Would you use it? How much would you pay?” Hypothetical money is Monopoly money. Watch what they did, not what they say they’d do.
Pitching mid-interview. Every minute describing your solution is a minute not learning, and it biases everything after. Stay in their world until the end.
Ignoring non-answers. “That’s interesting” plus no follow-up questions plus no ask for access means no. Treat lukewarm as no.
Interviewing fans. Friends, family and fellow founders encourage. Strangers with the problem and a budget decide — weight their words accordingly.

The pass criterion: concrete commitments — a follow-up meeting with their boss, an intro to three peers, a pre-sale, data access. Anything less than a commitment is encouragement, and encouragement does not validate (see willingness to pay).