L-2 spouses are employment-authorized incident to status and may work for any employer or themselves. Professional licensing in the U.S. state is a separate matter, and children in L-2 status may study but not work and lose status at 21.
Work is allowed; licensing and the children's ages are the planning items
The L-2 spouse of an L-1A transferee does not need a separate immigration case to take employment. Under current USCIS policy, employment authorization is incident to L-2 status, and the admission record annotated as an L-2 spouse serves as proof of it for an employer. A spouse who is a physiotherapist, an engineer or a bookkeeper can therefore accept a job, start a practice or consult, subject only to any state licence that profession requires, which is a practice question rather than an immigration one and should be started early because licensing boards move slowly.
Children may attend school at any level, may not work, including part-time or summer jobs, and lose L-2 status at 21 or on marriage. For a Sainte-Brigitte-de-Laval household with a child in the final years of secondary school, the transition to a student classification or a return to Canadian university should be planned before the assignment is accepted. Each dependant's admission period should be checked against the principal's after every entry, since a mismatch can end a spouse's authorization unexpectedly.