Writing paragraphs is an important part of academic writing courses required at the university level, as mastering paragraph writing is considered a fundamental step toward producing advanced formal and academic papers in the future. To become proficient in this skill, students, especially non-native English speakers, must make a special effort. This is because a good paragraph contains not only information, but also a variety of sentence types to engage the reader. With these qualities, paragraphs will capture the reader's attention and make the text easier to read. To find effective ways to help students write their paragraphs successfully and correctly, many research studies have analyzed paragraphs in terms of errors, grammar, sentence types, and sentence structures. The present study focuses on sentence-level analysis by examining paragraphs written by EFL students. Forty paragraphs written in English by second-year students majoring in English were analyzed for sentence types, as well as errors of grammar and mechanics. It was found that simple sentences were the dominant type, followed by complex sentences. Punctuation was the most common mechanical problem. The findings contribute to pedagogical implications, highlighting the necessity of raising awareness about the importance of sentence variety in paragraph writing. The correctness of grammar and the proper use of mechanics were also key issues for writing a good paragraph.