Photoemission electron microscopy (PEEM) is excellently suited for studying electronic excitations at surfaces by using fs laser pulses. When the photon energy of the used fs laser pulses (E∼3.1eV) is too low for threshold photoemission, photoemission must proceed via two photon photoemission (2PPE) through a virtual or real intermediate state. In our earlier work [1] we demonstrated that localized plasmon resonances (LSPs) in small Ag particles act as intermediate states for 2PPE and lead to enhanced photoemission. Here we focus on larger Ag islands, in which propagating surface plasmon polariton waves (SPPs) dominate the 2PPE signal [2]. Figure 1 shows an example for the resulting SPP contrast. Panel (a) shows a bright Ag island on a (√3 × √3)-Ag reconstructed Si(111) background in regular threshold photoemission. In 2PPE PEEM, shown in Fig. 1 (b), the contrast is completely changed. Panel (b) was recorded using ppolarized fs laser pulses in a grazing incidence geometry, i.e. the k-vector of the light, k_light, forms an angle of 74° with the surface normal. The incidence direction of the light k_light, and the in-plane component of the electric field vector are indicated at the bottom left of Fig. 1 (b).