The effects of alloying elements such as Mg, Cu, Ag, Ni, and Zn-added individually, or in combination, on the microstructure and phase precipitation in fourteen Al-11.7% Si alloys have been studied. Strontium (0.02–0.04 wt%) was used to produce well-modified structures. Beryllium (∼ 0.02%) was added to some alloys containing ∼ 0.4 wt% Mg to prevent oxidation, as well as to study its effect on fluidity and microstructure. Optical microscopy and electron probe microanalysis (EPMA), including energy dispersive X-ray (EDX) and wavelength dispersion spectroscopic (WDS) facilities were used to allow for a complete assessment of the microstructural changes and intermetallic phase precipitation occurring during solidification. Image analysis was used for quantification purposes. Thermal analysis was used to determine the precipitation reactions and temperatures of the various intermetallic phases formed. By measuring the size, shape, and density of the Si particles, the modifying effect of Sr and various other alloying elements was monitored.The modifying effect of Sr diminishes as the amount of added Cu and Mg is increased. In the Al-11.7% Si alloy containing ∼2.6% Cu and ∼ 0.4% Mg, additions of Ag, Ni, and Zn are found to improve the modification effect, with the Ag addition producing a Si particle density much higher than that achieved with Ni or Zn additions. Copper and Ni do not dissolve in the β-Al5FeSi iron intermetallic phase, but dissolve in measurable amounts in the α-iron Al15(Fe, Mn)3Si2 phase, and produce various Al- Ni-Cu intermetallics with different Al:Ni:Cu ratios, in addition to Al2(Ni, Cu).Also, the Al8MgCuSi phase is seen to precipitate separately, in the form of Chinese script, rather than growing out of the Al2Cu phase as is observed in the Ni-free alloys. Zinc is found to segregate at the boundaries of the α-Al dendrites, without forming any specific intermetallic.