A contractor has an obligation to complete work within the time for completion, and the employer should not impede the contractor in performing his or her obligations under the contract. To this end, if the contractor is prevented from completion by an act of prevention by the employer and there is no corresponding right to extend time for completion as a result of that act, or the time for completion is not properly extended, time becomes "at large." Accordingly, the contractor is not under the obligation to complete the work within the original time, although work should be completed within a reasonable time. This paper used a two-step research methodology where the time "at large" principle is explained within the context of the common law legal system and is consequently applied to various standard forms of contract. The standard forms of contract examined in this paper include the Joint Contracts Tribunal (JCT) Design and Build Contract of 2011, the World Bank Conditions of Contract (WB Contract) included in the Standard Bidding Documents for Procurement of Works (SBDW), the Federation of Consulting Engineers (FIDIC) Conditions of Contract for Construction issued in 1999, and the American Institute of Architects (AIA) Conditions of Contract for Construction (A201) of 2007. The authors highlighted the provisions related to delays and extension of time and mapped them to the principle of time at large to conclude when time could become at large under the subject contracts. This study helps employers and contractors who are entering into projects using any of these standard forms of contract within a common law legal system to avoid conflicts, claims, and disputes associated with or resulting from the time at large principle. This should support effective and efficient contract administration of construction projects.