Offer and Acceptance: One party must make an offer, and the other must accept it. In Pennsylvania, parties must acknowledge their acceptance in writing to safeguard against these uncertainties.The general rule is that a contract is effective when both parties agree (ie, sign the Agreement of Sale) AND acceptance is communicated to the offering party. The buyers provided a rather limited time for the sellers to consider their offer when they inserted a date in paragraph 5(a) of the agreement. In Pennsylvania, "the essential elements of a contract are an offer, acceptance, and consideration or a mutual meeting of the minds. In Pennsylvania, like many other states, verbal agreements can be legally binding depending on the situation.