Complex oxide interfaces are a promising platform for studying a wide array of correlated electron phenomena in low-dimensions, including magnetism and superconductivity. The microscopic origin of these phenomena in complex oxide interfaces remains an open question. Here we investigate for the first time the magnetic properties of semi-insulating NdTiO 3 /SrTiO 3 (NTO/STO) interfaces and present the first milli-Kelvin study of NTO/STO. The magnetoresistance (MR) reveals signatures of local ferromagnetic order and of spin-dependent thermally-activated transport, which are described quantitatively by a simple phenomenological model. We discuss possible origins of the interfacial ferromagnetism. In addition, the MR also shows transient hysteretic features on a timescale of ~10-100 seconds. We demonstrate that these are consistent with an extrinsic magneto-thermal origin, which may have been misinterpreted in previous reports of magnetism in STO-based oxide interfaces. The existence of these two MR regimes (steady-state and transient) highlights the importance of timedependent measurements for distinguishing signatures of ferromagnetism from other effects that can produce hysteresis at low temperatures.The interface between two complex oxides can host a high-mobility conducting electron gas, even though the constituent materials are insulators. Since the initial discovery of this phenomenon in LaAlO 3 /SrTiO 3 (LAO/STO) heterostructures [1], several other materials systems with this property have been identified [2][3][4]. These systems host a range of highly-correlated phases, including superconductivity [5,6] and ferromagnetism [7][8][9][10][11][12]. While superconductivity has been conclusively detected using transport [5,6,8,13] and scanning-probe measurements [9], reports of magnetism have been more difficult to reconcile across experiments. Numerous studies have investigated the magnetic properties of this class of oxide interfaces, with the majority of work to date focusing on the canonical LAO/STO system [7][8][9][10]14]. However, a unified picture of ferromagnetism is still lacking [7][8][9][15][16][17][18].Magneto-transport studies [7,10,19], have reported pronounced magnetic hysteresis, suggestive of