Are construction contract "pay when paid" clauses enforceable?

Yes, they are... Although somewhat unfair, Florida Courts have enforced these clauses provided the language clearly and unambiguously states that the contractor does not have to pay the subcontractor/supplier until the contractor receives payment from the owner or lender. The key to enforcing these "pay when paid" clauses is that they be clear and unambiguous. Subcontractors and material suppliers should definitely stay away from these types of clauses.