1. According to Cambridge: a credit to someone/something Meaning in the Cambridge English Dictionary a credit to someone/something to be so good or successful that the people or things that made you successful should be mentioned: (A) Thomas is a credit to our school. According to the definition, I understand: Thomas is a good/successful person and our school has helped Thomas be good/successful. And Thomas owes his success to our school. 2. According to Macmillan be a credit to someone (phrase) definition and synonyms | Macmillan Dictionary be a credit to someone (in this definition, the dictionary doesn't refer to "be a credit to something", but I think they are the same) if you are a credit to someone connected with you, or if you do them credit, they should be proud of you (A) Thomas is a credit to our school. According to the definition, I understand: Our school is proud of Thomas because he, a successful person, is a member of our school. In this definition, the sentence doesn't say that our school help Thomas be successful or that Thomas owes his success to our school. Maybe he is an inborn talent, so, if he is not the member of our school, he is still successful. 3. According to OALD credit_1 noun - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com The meaning No.8: [singular] credit to somebody/something a person or thing whose qualities or achievements are praised and who therefore earns respect for somebody/something else (A) Thomas is a credit to our school. I understand: Thomas is a successful person, and he has been already praised for his success. So he earns respect for our school, that is to say, our school get respect because we have a member like Thomas. The sentence doesn't say that our school help Thomas be successful or that Thomas owes his success to our school. Maybe he is an inborn talent. It seems that the definitions of Macmillan and OALD are the same. I wonder if my observations are correct and which is the precise meaning of "A is a credit to B" Thank you for taking the trouble to help me.