You are correct that changes to the object will be reflected in the calling code. But that's the nature of the reference, not whether it is called by value or c

You are correct that changes to the object will be reflected in the calling code. But that's the nature of the reference, not whether it is called by value or called by reference. Whether you pass a reference by value or by reference, the changes to the object will be reflected in the calling code. And as I noted, it's all passed by value in C# unless you use modifiers ( ref or out ). The difference between "pass by value" and "pass by reference" for reference variables is how the variables themselves are handled. For example, if you pass a reference "by reference" to a function and set it to null, then the reference variable in the calling code is also set to null and will cause null ref exception if you try to access the object. Whereas if you pass a reference "by value", if you set the variable to null, the calling code variable isn't affected. Pass by value and pass by reference is not about objects or types really, it's about variables.