In my opinion, psychology is definitely a science. "Science" is when we test out ideas in a controlled way, and learn about their outcomes, to understand how the world works. This is exactly what we do in psychology.
We can set up controlled experiments, where the researchers actually manipulate 1 variable, and test to see what the outcome is. From the results, we are then able to make an educated conclusion, and hopefully apply it to the real world.
Science is actually defined as ""knowledge attained through study or practice". According to: http://www.sciencemadesimple.com/science-definition.html, "science is uses observation and experimentation to describe and explain natural phenomena." This is the basis of psychology.
One major methodology in psychological research is called ...
Evidence validates psychology as a science in this posting. References are also provided to justify the assertions.